Rectangular Battery Pack Spacer Layout for Electrolyte Leakage Control

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Solution Overview

Problem

Existing battery packs with rectangular secondary batteries experience electrolyte leakage due to uneven expansion and contraction during charging and discharging, leading to degradation of high-rate properties, as spacers only press the end portions and not the center, where expansion is greatest.

Innovation Solution

A battery pack design that includes spacers with first pressing portions at both ends and a second pressing portion along the winding axis, pressing the center portion, to evenly distribute pressure and reduce electrolyte leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If a battery pack is designed to fit into a limited space, then the volume is reduced, but the heat dissipation capability deteriorates

Engineering Contradiction:
Improvebattery pack volumeVSAvoidheat dissipation
Core Design Contradiction:
Volume of moving objectVSTemperature

Solution Approach 1:

The battery pack is divided into multiple battery modules, each with its own cooling channels. The cooling system is segmented into first cooling channels within battery modules and second cooling channels within the housing, allowing distributed heat dissipation that maintains effectiveness in compact volumes.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Cooling channels are implemented in multiple spatial dimensions - first cooling channels extend along the length of battery modules while second cooling channels are arranged in the width direction within the housing. This multi-dimensional cooling architecture maximizes heat dissipation surface area within limited volume.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Volume of moving object

If battery modules are arranged closely to reduce volume, then the compactness is improved, but the heat accumulation increases

Engineering Contradiction:
Improvebattery pack volumeVSAvoidheat accumulation
Core Design Contradiction:
Volume of moving objectVSObject-generated harmful factors

Solution Approach 1:

A housing structure acts as an intermediary between battery modules, providing integrated cooling channels that flow coolant between adjacent modules. This intermediary cooling system effectively removes heat that would otherwise accumulate due to close module arrangement.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

A liquid cooling system using coolant circulation through embedded channels provides active thermal management. The hydraulic cooling system efficiently transports heat away from densely packed battery modules, preventing heat accumulation despite reduced spacing.

Inventive Principle:
Principle #29Pneumatics and hydraulics

3Temperature

If cooling channels are added to improve heat dissipation, then the temperature control is improved, but the device complexity increases

Engineering Contradiction:
Improveheat dissipationVSAvoidcooling system complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The housing structure is merged with the cooling system, with cooling channels directly integrated into the housing walls. This combination eliminates the need for separate cooling components, reducing overall system complexity while maintaining effective heat dissipation.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The housing serves multiple functions: structural support, protection, and thermal management through integrated cooling channels. This multi-functionality reduces the need for additional dedicated cooling components, simplifying the overall device architecture.

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

The design effectively reduces electrolyte leakage and maintains high-rate properties by evenly distributing pressure across the electrode body, improving resistance and reducing electrolyte depletion.

Implementation Method 1

a first cooling channel extending along a length of the first battery module and a second cooling channel extending along a width of the housing

Methodology Applied
Scientific EffectHeat conduction: Conduction (thermal)

Data Source

PatentEP4120409B1Battery pack
Publication Date: 2026.04.08 SANYO ELECTRIC CO LTD
  • EP4120409B1 patent drawingFigure 1(a)~1(d)
  • EP4120409B1 patent drawingFigure 2
  • EP4120409B1 patent drawingFigure 3

AI summary

A battery pack includes a plurality of rectangular secondary batteries arranged in a state in which the plurality of rectangular secondary batteries is pressed against each other in an arrangement direction through spacers. Each rectangular secondary battery is configured such that a flat wound electrode body is housed in a battery case with a winding axis extending parallel with a long side surface of the battery case. The electrode body has a flat portion in which positive and negative electrode material mixture layers face each other with a separator interposed therebetween. The spacers include a pair of first pressing portions pressing both end portions of the long side surface, which faces the flat portion, of the battery case in a winding axis direction along a direction perpendicular to the winding axis, and a second pressing portion pressing a portion of the long side surface along the winding axis between the pair of first pressing portions.