Battery Cell Housing Bottom Venting for Higher Energy Density

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Solution Overview

Problem

Existing lithium-ion cells, particularly cylindrical round cells, suffer from suboptimal energy density due to dead volumes at the ends of the winding, which are bridged by arrester strips, and lack efficient integration into cell assemblies with compact and safe electrical connections.

Innovation Solution

The energy storage element features an airtight and liquid-tight housing with integrated overpressure protection, where the anode and cathode current collectors have free edge strips, allowing direct electrical connection to the housing bottom, and the lid component is used for compact assembly, enabling efficient electrical contact and safety mechanisms.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If arrester strips are used to bridge dead volumes at the ends of the winding, then electrical connection is achieved, but energy density decreases due to suboptimal space utilization

Engineering Contradiction:

Improveelectrical connectionVSAvoidenergy density

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The invention extracts the arrester strips from the system and replaces them with direct electrical connection of the current collectors to the housing bottom. This removes the dead volume occupying space at the ends of the winding, allowing better space utilization and improved energy density while maintaining reliable electrical connection through the current collectors themselves.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The current collectors are given a dual function: they serve both as electrical conductors and as structural elements that directly connect to the housing bottom for electrical connection. This eliminates the need for separate arrester strips and maximizes the utility of the current collector components, improving both electrical connection reliability and energy density.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Quantity of substance

If current collectors are directly connected to housing bottom, then dead volume is minimized and energy density improves, but manufacturing complexity increases

Engineering Contradiction:

Improveenergy densityVSAvoidmanufacturing complexity

Core Design Contradiction:

Quantity of substanceVSEase of manufacture

Solution Approach 1:

The invention merges the electrical connection function and structural support function into a single integrated design where the current collectors directly contact the housing bottom. This consolidation eliminates the need for separate arrester strips and simplifies the assembly process, reducing manufacturing complexity while maximizing energy density.

Inventive Principle:

Principle #5Merging (Combining)

3Adaptability or versatility

If lid component is used for compact assembly, then integration into cell assemblies is improved, but device complexity increases

Engineering Contradiction:

Improveintegration capabilityVSAvoidassembly structure

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The lid component is designed with multi-functionality, serving both as a structural closure and as an electrical connection element. This integrated design improves adaptability for compact cell assembly integration while avoiding the need for additional separate electrical connection components, thereby not increasing overall device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 energy density and safety by minimizing dead volumes and allowing efficient integration into cell assemblies with compact electrical connections and overpressure protection, improving the cell's ability to handle high currents and maintain structural integrity.

Implementation Method 1

The housing bottom has an aperture closed by a metallic membrane that acts as a primary protection device against internal overpressure

Methodology Applied

Scientific EffectOverpressure protection:

Implementation Method 2

the housing bottom has at least one groove on its inside or outside that acts as a secondary protection device against internal overpressure

Methodology Applied

Scientific EffectStress concentration:

Implementation Method 3

Electrochemical energy storage elements can convert stored chemical energy into electrical energy through virtue of a redox-reaction

Methodology Applied

Scientific EffectRedox reaction: Redox Reactions

Implementation Method 4

This ion current crosses the separator and is made possible by an ion-conducting electrolyte

Methodology Applied

Scientific EffectIon conduction: Conduction (electrical)

Data Source

PatentUS20250273779A1Energy storage element and manufacturing process

Publication Date: 2025.08.28 VARTA MICROBATTERY GMBH

AI summary

An energy storage element includes a housing having a metallic, cup-shaped housing part with a housing bottom and a lid component that closes a terminal opening of the cup-shaped housing part. The energy storage element further includes an electrode-separator assembly arranged in the housing, the electrode-separator assembly comprising a first flat terminal end face, a second flat terminal end face, an anode with an anode current collector having a first edge and a second edge parallel thereto, and a cathode with a cathode current collector having a first edge and a second edge parallel thereto. The housing bottom has an aperture closed by a metallic membrane that acts as a primary protection device against internal overpressure, and at least one groove on its inside or outside that acts as a secondary protection device against internal overpressure.