Separator Edge Sealing for Battery Short Circuit Prevention

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Solution Overview

Problem

Energy storage devices with layered structures face issues such as electrical short circuits and susceptibility to perforation due to the use of multilayer composite films and printing paste-based separator-electrolyte layers, respectively.

Innovation Solution

The energy storage device employs a porous surface structure with a central electrolyte-filled region and an edge region without electrolyte, combined with a sealing frame formed from a sealing agent applied to the edge of a porous sheet-like structure, which is more resistant to perforation and eliminates short circuits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a sealing frame is used to seal the electrode-separator stack, then sealing is achieved, but electrical short circuits occur in the area of connection contacts due to pressure and elevated temperatures

Engineering Contradiction:
Improvesealing effectivenessVSAvoidelectrical short circuits
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The sealing frame is divided into two distinct regions: a first region that seals the electrode-separator stack without causing short circuits, and a second region that provides thermal activation for sealing. This segmentation allows the sealing function to be separated from the electrical contact area, preventing harmful electrical short circuits while maintaining effective sealing through thermal activation in the dedicated second region.

Inventive Principle:
Principle #1Segmentation

2Manufacturing precision

If printing paste is used to produce separator-electrolyte layers, then thin layers can be manufactured, but susceptibility to perforation increases

Engineering Contradiction:
Improvelayer thickness controlVSAvoidresistance to perforation
Core Design Contradiction:
Manufacturing precisionVSStrength

Solution Approach 1:

The separator-electrolyte layer is formed as a composite structure combining printing paste with additional reinforcing materials. This composite approach maintains the thin layer capability provided by the printing paste while incorporating materials that significantly enhance resistance to perforation, thus resolving the contradiction between manufacturing precision and structural strength.

Inventive Principle:
Principle #40Composite materials

3Reliability

If multilayer composite films with thin metal barrier layers are used, then sealing is achieved, but electrical short circuits occur due to pressure and elevated temperatures during sealing

Engineering Contradiction:
Improvesealing effectivenessVSAvoidelectrical short circuits from metal layers
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The sealing frame is designed with spatially varying properties: the first region has properties optimized for sealing without causing short circuits, while the second region has properties optimized for thermal activation. This local differentiation ensures that the metal barrier layers are protected from conditions that would cause short circuits, while still achieving effective sealing through the thermally activated second region.

Inventive Principle:
Principle #3Local quality

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 configuration enhances the structural integrity and prevents electrical short circuits, making the energy storage device more reliable and durable.

Implementation Method 1

which ensures an ion current between the electrodes during charging and/or discharging of the energy storage device

Methodology Applied
Scientific EffectIon conduction: Conduction (electrical)

Implementation Method 2

a circumferential sealing frame formed from a sealing agent applied to the porous sheet structure

Methodology Applied
Scientific EffectAdhesion: Adhesive

Data Source

PatentEP3477727B1Energy storage device and method of manufacturing same
Publication Date: 2021.01.20 VARTA MICROBATTERY GMBH
  • EP3477727B1 patent drawingFigure 1A~1D
  • EP3477727B1 patent drawingFigure 2

AI summary

An energy storage device (100) comprises an assembly (101) of a layered positive electrode (102), a layered negative electrode (103), and a layered separator (104) arranged between the layered positive electrode (102) and the layered negative electrode (103), a housing (105) comprising a first housing part (106) and a second housing part (107), and an electrolyte that ensures an ion current between the electrodes (102, 103) during charging and/or discharging of the energy storage device (100). The electrodes (102, 103) each comprise an electrochemical active component. The layered separator (104) comprises a porous sheet structure (105).The energy storage device (100) is characterized by the fact that the porous sheet structure (105) comprises a central region (105a) in which its pores are filled with the electrolyte, and a strip-shaped peripheral region (105b) surrounding the central region (105a) in which the pores of the porous sheet structure (105) are not filled with the electrolyte. The first housing part (106) and the second housing part (107) are connected to each other by means of a circumferential sealing frame (108) formed from a sealing agent applied to the porous sheet structure (105) in the peripheral region (105b). To manufacture the energy storage device (100), a separator-sealing frame unit is formed by applying the sealing agent to the strip-shaped edge area (105b), which is combined with the layered positive electrode (102) and the layered negative electrode (103) to form the composite (101).