ESS Module Flow Path Barriers for Thermal Runaway Flame Blocking

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Solution Overview

Problem

ESS modules face challenges in preventing flame propagation to adjacent battery cells during thermal runaway while ensuring smooth gas discharge, especially when air cooling is used, as heat and flame can easily spread along the flow path formed between stacked battery cells.

Innovation Solution

The ESS module incorporates mica barrier assemblies and expandable graphite sheets that form and block flow paths based on temperature, preventing flame propagation while allowing gas discharge, using a combination of mica barriers, mesh barriers, and strategically placed plates to manage airflow and gas venting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If air cooling is used with flow paths along stacking direction, then cooling efficiency is improved, but flame propagation risk increases

Engineering Contradiction:

Improvecooling efficiencyVSAvoidflame propagation risk

Core Design Contradiction:

TemperatureVSObject-affected harmful factors

Solution Approach 1:

The flow path is segmented into multiple sections by mica barrier assemblies positioned between adjacent battery cells. Each segment allows independent control of cooling and flame prevention functions, enabling the system to maintain cooling efficiency while blocking flame propagation paths.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The mica barrier assemblies dynamically change their state based on temperature: remaining open during normal operation to allow cooling airflow, and closing when temperature reaches a threshold to block flame propagation. This dynamic response resolves the contradiction between continuous cooling and flame prevention.

Inventive Principle:

Principle #15Dynamics

2Ease of operation

If flow paths are formed for gas discharge, then gas venting is improved, but flame exposure risk increases

Engineering Contradiction:

Improvegas discharge smoothnessVSAvoidflame exposure risk

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

Mica barrier assemblies act as intermediary components between the flow path and external environment. They maintain open flow paths for gas discharge while serving as fire barriers that prevent flame exposure, thus resolving the contradiction between gas venting efficiency and flame safety.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Object-affected harmful factors

If mica barrier assemblies are added to block flame, then flame propagation prevention is improved, but device complexity increases

Engineering Contradiction:

Improveflame propagation preventionVSAvoidmodule structure complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The mica barrier assemblies utilize temperature as a triggering parameter to automatically change from an open state (allowing cooling and gas discharge) to a closed state (blocking flame). This parameter-based control eliminates the need for complex active control systems while achieving flame propagation prevention.

Inventive Principle:

Principle #35Parameter changes

4Object-affected harmful factors

If expandable graphite sheets are used to fill flow path grooves, then flame blocking is improved, but gas discharge capability may be reduced

Engineering Contradiction:

Improveflame blocking effectivenessVSAvoidgas discharge capability

Core Design Contradiction:

Object-affected harmful factorsVSEase of operation

Solution Approach 1:

Expandable graphite sheets undergo a phase transition from a compact state to an expanded state when exposed to high temperatures. In the expanded state, they effectively block flames while the timing and characteristics of this transition are controlled to maintain gas discharge capability during normal thermal runaway events.

Inventive Principle:

Principle #36Phase transitions

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 effectively cools battery cells, ensures smooth gas discharge during normal operation, and prevents flame propagation to adjacent cells during thermal runaway, enhancing safety by blocking flame paths when temperatures rise.

Implementation Method 1

a first expandable graphite sheet configured to fill a part of the flow path groove, the first expandable graphite sheet being expanded at a temperature equal to or higher than the reference temperature to fully fill the flow path groove

Methodology Applied

Scientific EffectExpandable graphite expansion: Thermal Expansion

Implementation Method 2

one of the mica barrier assemblies is provided between adjacent battery cells and at an outermost side of the cell stack to form a flow path along a stacking direction of the cell stack at a temperature lower than a reference temperature

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS11881592B2ESS module having structure capable of preventing external exposure of flame and ESS pack including the same

Publication Date: 2024.01.23 LG ENERGY SOLUTION LTD

AI summary

An Energy Storage System (ESS) module includes a cell stack assembly including a cell stack formed by stacking a plurality of battery cells and a plurality of mica barrier assemblies and a pair of bus bar frames coupled to both side portions of the cell stack; and a housing configured to accommodate the cell stack assembly and having a plurality of flow path holes formed at locations corresponding to a front side, a rear side and both side portions of the cell stack assembly, wherein the mica barrier assembly is provided between adjacent battery cells and at an outermost side of the cell stack to form a flow path along a stacking direction of the cell stack at a temperature lower than a reference temperature and to block the flow path at a temperature equal to or higher than the reference temperature.