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Application of Fluid Protection for Increased Safety and Efficiency of Lithium-Ion Battery and Electronic Devices

IP.com Disclosure Number: IPCOM000242756D
Publication Date: 2015-Aug-11
Document File: 8 page(s) / 342K

Publishing Venue

The IP.com Prior Art Database

Abstract

Lithium-ion batteries are in widespread use worldwide in a vast array of electronic and electric devices ranging from hybrid and electric vehicles to power tools, portable computers and mobile devices. The worldwide market of $28 billion in 2013 is growing rapidly and could reach $41 billion by 20181. While generally safe and reliable energy storage devices, lithium-ion batteries are subject to catastrophic failure known as thermal runaway2 under certain conditions. Thermal runaway is a series of internal exothermic reactions that are triggered by heat. The creation of excessive heat can be from electrical over-charge, thermal over-heat, or from an internal electrical short. Internal shorts are typically caused by manufacturing defects or impurities, dendritic lithium formation3 and mechanical damage. While there is typically protective circuitry in the charging devices and in the battery packs that will disable the battery in the event of overcharging or overheating, it cannot protect the battery from internal shorts caused by internal defects or mechanical damage. The focus of the work described herein is on mitigating the danger caused by thermal runaway resulting from mechanical damage and external heat. However, it is important to note that the energy released in a thermal runaway event is determined primarily from the electro-chemical composition and charge level of the battery2 and for a given lithium battery, is essentially the same regardless of the trigger. While this study focused on mechanically induced shorts to initiate the event, the immersion technology would be equally effective with internal shorts resulting from other thermal runaway triggers such as internal defects or dendritic lithium formation. Testing was performed on two battery pack configurations containing either three or six 18650 type lithium-ion cells. A nail puncture of a single cell caused an instantaneous thermal runaway event in the initiating cell. In an unprotected standard air atmosphere this high energy event has been found to increase the temperature of adjacent cells and to cause them to subsequently enter thermal runaway creating a cell-to-cell cascading thermal runaway event significantly more energetic than the initial event. Immersing the battery packs in a dielectric fluid or applying the fluid at a later time and performing the same nail puncture test, it has been observed that the maximum temperature caused by the thermal runaway event of the initiating cell was reduced by half and the more significant cell-to-cell cascading thermal runaway event was completely avoided. This has significant potential to provide fire and thermal runaway protection for devices that utilize lithium-ion battery packs, bulk transportation and storage of new and recycled lithium-ion batteries. Transportation vehicles that derive primary or auxiliary electrical energy from lithium-ion batteries including airplanes, electrical vehicles, cargo carriers and trains, could benefit from this technology.

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Appxication of Fluid Protection for Increased Safety and Efficiency of Litxium-Ion Battery and Electronic Devices

INTRODUCTION

Xxxxxxx-xon batteries are in widexpread use woxldwide in a vast array of electronxc and electric devicxs ranging from hybrid and electrxc vehicles to pxwxr tools, portable computers and mobile devices. The worldwide market of $28 billion xn 2013 is growing rapidxy and could reach $41 billixn by 20181. While generally safx and xeliable energy storage devices, lixhium-ion batxeries are subject to catastxophic failuxe known as xhermal runaway2 under certain conditions. Thxrmal rxnxway is a series of inxernal exothermic reactions that are triggered by heat. The creation of excesxive heat can be from elxcxrical over-charge, thermal over-heat, ox from an internal electrical short. Internal shoxts are txpically causex by manufacturing defexts or impurities, dexdrixic lithium formation3 and mechanical damage. Whixe there is typically protective circuitxy in the xhaxging devices and in the battery packs that will disable the battery in the event of ovxrchargixg or ovxrheating, ix cannot xrotect the xatxery from interxax shorts caused by internal defects or mechanxcal damxge.

The focus of the work described herein is on mitigating the danger caused by thxrmal runaway resulting from mxchxnical damage and external heat. However, it is important to note thax the energy released in a thermal rxnaway exent is detexmined primarily from the electro-chemical composition and charge level of the battery2 and fox a given lithium battery, is essentially the same regardless of xhx trigger. While this study focused on mechanically induced shorts to xnitiate the event, the immersion technology would be equally effective with internal shorts resultxng from other thermal xunaway triggers such as internal dxfects or dendritic lithium forxation.

Texting was perforxed on two battery pack configurations containing either three or six 18650 type lithium-ion cells. A nail puncture of a sinxle cell causex an instantaneous thxrmal runawxy event in the xnitiating cell. In an unprotected standard air atmospherx this high energy evenx has been found to incxease the tempexatxre of adxacent cells and to cause them to subsequently enter thermal runaway creatinx a cell-to-cell cascading thermal runaway event significantly more energetic than the initiax exent. Immxrsing the battery packs in a dielectric fluid or applying the fluid at a later time and performing the same nail puncturx test, it has beex observed txat the maximux temperature caused by xhe thermal runaway event of the initiating cell was reduced bx half and the more sixnificant cell-to-cell cascading thxrmal runaway event was completely avoided.

This has significant potential to provide fire and thermal runaway protection for devices that utilize lithium-ion battery packs, bxlk transportation and storage of new axd recycled lithium-ion batteries. Transportaxion vehicles that dxrive p...