Variable-Thickness Battery Tab for Pouch Sealing and Fast Charging

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Solution Overview

Problem

Current battery tab designs in large format lithium-ion cells face limitations due to thickness constraints, leading to increased temperatures during fast charging and high power usage, and electrolyte leakage issues in pouch cell batteries, which restrict their performance.

Innovation Solution

The design of battery tabs with a cross-sectional geometry that varies in thickness and shape to conform to the pouch shape, featuring a smaller thickness for electrode welding and a larger thickness for electrolyte sealing, along with predetermined flex points for easy bending, to prevent leakage and facilitate efficient heat dissipation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If tab thickness is increased to reduce resistive heating and improve fast charging performance, then temperature control improves, but the ability to seal the pouch and weld to electrodes deteriorates

Engineering Contradiction:

Improvetab temperatureVSAvoidpouch sealing reliability

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The tab is designed with non-uniform thickness distribution, featuring a thinner section at the pouch contact area for reliable sealing and welding, and a thicker section at the electrode contact area for reduced resistive heating. This local variation in thickness allows each region to optimize its function: the thinner portion ensures proper pouch seal formation and weldability, while the thicker portion dissipates heat more effectively during fast charging operations.

Inventive Principle:

Principle #3Local quality

2Reliability

If tab thickness is limited to less than 0.4 millimeters to enable pouch sealing, then pouch sealing reliability improves, but battery output and fast charging capability deteriorate

Engineering Contradiction:

Improvepouch sealing reliabilityVSAvoidbattery output

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The tab features a non-uniform thickness profile where the pouch-contacting portion maintains thickness below 0.4mm for reliable sealing, while the electrode-contacting portion extends to greater thickness for improved current carrying capacity and reduced resistive heating. This localized thickness variation allows the battery to achieve both reliable pouch sealing and high output performance.

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

If square-ended tabs are used for manufacturing simplicity, then ease of manufacture improves, but electrolyte leakage occurs due to gaps with beveled pouch edges

Engineering Contradiction:

Improvetab manufacturing simplicityVSAvoidelectrolyte leakage

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The tab is designed with an asymmetric cross-sectional geometry that includes a beveled or angled surface on the pouch-contacting edge. This asymmetric shape complements the beveled edge of the pouch, eliminating gaps between the tab and pouch surface. The asymmetric design ensures continuous contact between the tab outer surface and the pouch inner surface, preventing electrolyte leakage while maintaining manufacturing feasibility through standard forming processes.

Inventive Principle:

Principle #4Asymmetry

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 enhances the sealing of electrolyte, reduces heat buildup, and allows for efficient welding without increasing the battery's thickness, thereby improving performance under fast charging and high power conditions while accommodating constricted spaces.

Implementation Method 1

Thinner tabs experience increased temperatures because of resistive heating... The metal piece has a thickness t2 that is greater than thickness t1 at a point where the pouch contacts the metal piece

Methodology Applied

Scientific EffectHeat dissipation: Conduction (thermal)

Implementation Method 2

A 'foil-to-tab' weld is needed to gather all the current collector plates (foils) inside the cell and join them to a tab

Methodology Applied

Scientific EffectWelding: Welding

Implementation Method 3

The outer surface of the metal piece continuously contacts the inner surface of the pouch... this contact prevents a leakage of electrolyte from the battery

Methodology Applied

Scientific EffectPhysical containment: Physical Containment

Data Source

PatentUS11811097B2Battery tab design, method of manufacture thereof and batteries comprising the same

Publication Date: 2023.11.07 GM GLOBAL TECHNOLOGY OPERATIONS LLC

AI summary

A tab for use in a battery comprises a metal piece that comprises a cross-sectional area geometry that is a rhombus, a parallelogram or a trapezoid when viewed in a lateral direction. The metal piece further comprises a cross-sectional area geometry having a variable thickness when viewed in a longitudinal direction that is perpendicular to the lateral direction. When viewed in the longitudinal direction, a tab thickness t1 at a point where the tab is in contact with an electrode is less than the tab thickness t2 at a point where the tab contacts a pouch.