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Lithium Ion Battery FiresHugh Hurren - Hartwood Consulting
Introduction
● Lithium Ion (or Lithium Polymer, LiPo) batteries are used in many electronic devices
● Have recently seen widespread use in automotive, aerospace and electrical power storage
● First proposed in the 1970’s● First commercialised by SONY in 1991
World-Wide Battery Market Growth
From AVICENNE, high growth technology consultants based in France
Li Ion
Lithium Ion Battery Chemistry
Lithium Ion Batteries typically contain:
● A Copper Anode with Graphite on its
surface
● An Aluminium Cathode with a varying
form of Lithium Oxide on its surface
● A Polymer semi-porous separator in
between the two preventing direct contact
of the electrodes
● A liquid electrolyte to facilitate Lithium Ion
transfer (proprietary) Ho Sop Shin, Degradation Mechanisms Of electrode/Electrolyte Interfaces In Li-ion Batteries, 2015
Reaction Example
Australian academy of science: https://www.science.org.au/curious/technology-future/lithium-ion-batteries
Battery degradation from normal charge and dischargeOver time Lithium ion batteries lose capacity.
The most common way this occurs is from Solid Electrolyte Interphase (SEI) formation on the Anode.
This is a deposited layer of various chemical compounds (depending on the chemistry of the battery)
which impedes Lithium ion movement, raises internal resistance of the cell.
https://www.sciencedirect.com/science/article/abs/pii/S2542435119304210
Degradation of a Panasonic cell after repeated cycling:
https://goughlui.com/2020/02/07/project-torture-of-an-old-panasonic-cgr18650cg-using-rs-ngm202/
After 800 charge/ discharges, the cell loses almost all capacity
Other degradation mechanisms
At Rest:
● Chemistry (compatibility of materials)
● Time (chemical reactions can occur over time)
● State of Charge (Li content can affect chemical and structural stability)
● Temperature (chemical reactions are temperature dependant)
During Use:
● Cell structure/layout (the arrangement and design of batteries in series and parallel can affect
characteristics)
● Charge/Discharge Rate (increased rates create heat, dendrites through separator)
● Depth of Discharge (can affect electrode volume chance and create heat)
● Heat (can accelerate chemical reactions)
According to IEEE presentation: Performance, Safety & Degradation of Li-ion Battery Storage, presented 21 May 2020 by Daiwon Choi, Vish Viswanathan
Problems with fast charging:
Recent study by Sebastian et al. from University of
California (November, 2019)
Determined that industry standard lithium ion
battery charging (typically for electric car charging)
significantly degrades Lithium ion batteries.
Determined that charging should depend on the
internal resistance of the battery (extra capacity,
lower temperatures, increased safety at the cost of
slower charging)
Research into charging is still evolving.
https://onlinelibrary.wiley.com/doi/pdf/10.1002/est2.141
Typical Battery materials
● According to ProSUM, a project
funded by the EU and Switzerland
spanning from 1 January 2015 and
ran for 36 months until the end of
2017, found the typical material
concentrations to be →
https://www.rechargebatteries.org/wp-content/uploads/2018/05/RECHARGE-The-Batteries-Report-2018-April-18.pdf
Lithium
Chemistry overview (typical numbers)
Lithium Manganese Oxide
From battery university:https://batteryuniversity.com/learn/article/types_of_lithium_ion
Lithium Nickel Manganese Cobalt Oxide(Popular)
Lithium Iron Phosphate (Newer)
Lithium Nickel Cobalt Aluminium Oxide (Newer, used by Tesla)
Lithium Cobalt Oxide (Older)
LiCoO24.2V Charged2.5VDepleted
LiNiMnCoO24.2~4.3V Charged2.5VDepleted
LiNiCoAlO24.2V Charged2.5VDepleted
LiMn2O44.2V Charged2.5VDepleted
LiFePO43.65V Charged2.5VDepleted
Types of Lithium Ion Batteries
Lithium Ion Cell (Cylindrical)
Lithium Ion Cell (Flat Packed, ‘Pouch cell’)
Portable device Lithium Ion battery
‘LiPo’ Battery Lithium Ion Prismatic cell
Power tool batteries, E-cigarettes, torches, laptop batteries, Tesla battery packs
Portable electronics, laptop batteries
Mobile Phones, Digital cameras
Drones, Radio controlled cars
Automotive, Aerospace (787 Dreamliner), Power storage applications
18650 Cell
18650 is a popular cylindrical form factor Lithium Ion cell
stands for diameter “18”mm x length “65”mm
Encased in a steel case with a vent at the positive terminal and coated in a plastic sleeve
Capacity maxes out at around 3500mAh at 3.6V or 12.6Wh
Used in battery packs for laptops, power tools, power banks, also Tesla batteries
Flat pack cells
Commonly used in portable electronics like Phones, Laptops, Drones etc.
Can be a variety of dimensions
Are usually sealed, preventing gases from escaping
Typically bulge when internal gases are produced from side reactions as a result of overcharging, over discharging (if in series connection with other batteries) and repeated cycling
Lithium Ion Battery structure
Taken from a recent inspection of a fire damaged cordless drill battery pack:
Copper Anode w/ Graphite
Polymer Separator
Aluminium/Lithium Oxide Cathode
Polymer Separator
Counterfeit detection - weightOften, the contents of fake Lithium Ion cells are less dense
Therefore the quickest way of checking is weight comparison with a known genuine cell
The below test is done with similar advertised capacity cells:
Fake 18650 Real 18650From https://www.youtube.com/watch?v=JC2QcrMrqlU
Counterfeit detection - capacityThe second way of checking is capacity testing, depending on
the type of battery this can be tricky.
- For USB charge devices, cheap USB meters exist with
reasonable accuracy
- For cylindrical cells, some chargers have dedicated
capacity detection
- Lipo batteries have chargers that can analyse the
capacity and characteristics:
Counterfeit Detection - internal examinationThe most complex and risky way to know if a cell is genuine is to observe the electrode foil contents
Scientists and researchers in Lithium Ion development typically use x-ray scanning for non destructive
examination:
Video from https://www.youtube.com/watch?reload=9&v=z5bLLbik6ls
Part of the following study:Tracking Internal Temperature and Structural Dynamics during Nail Penetration of Lithium-Ion Cells, http://jes.ecsdl.org/content/164/13/A3285.full.pdf+html
Destructive testing an 18650 Lithium Ion cell, using a heat sensing nail driven into the side of the cell:
Internal examination continued
Physical examination of the internals can be useful, but destructive to the evidence and there is a risk of
hazardous material exposure.
Opening up an 18650 cylindrical cell to find loosely packed electrode foil, which would result in less capacity
Fromhttps://www.youtube.com/watch?v=JC2QcrMrqlU
Electronic Battery ProtectionOne of the most common ways of limiting degradation mechanisms to to add electronics that provide protection to the cell.
● For single cells, a protection circuit: ● For many cells together, a BMS (Battery Management System) for batteries in series
● Cell balancing is done by a BMS
Mechanical Battery Protection
Another method of protection in 18650 Cells is to use
mechanical protection mechanisms
One is called a CID (Current Interrupt Device),
● Valve which pops open when gas pressure inside the cell is
excessive.
● This ‘pop’ then cuts the current from the cell
There is also a device called a PTC (Positive Temperature
Coefficient)
● A ring around the positive terminal
● Increases resistance in response to temperature from
current surges
CID (Current Interrupt Device)
Positive Temperature Coefficient
For cylindrical cells only
Fire causes in batteries
Lithium Ion cells need to operate under strict conditions
● They have a small voltage window (~3.6-4.2v)
● Over-charging or over-discharging → Accelerated
Degradation
● Can’t handle too much current● Long term storage is an issue
○ Sensitive to extreme temperatures (<-20℃,
>60℃)
● Occasionally manufacturing defects can occur
Combine these factors together and fire risk increases
Main Failure Modes
Mode of Failure Potential causes
Separator puncture - Sharp object penetration
Separator fracture - Bending of cell
Separator melting - Excessive heating
Dendrites through separator - Overcharging, electrode materials
ingress
through separator
Gas release - Breakdown of Cathode
or electrolyte solvents via overcharging
Gases can be flammable
External short circuit - Surface contamination,
Shorting the + and -,
Degradation of insulation between + and -
From Exponent report on Samsung note 7 fires,
Short circuit occurred via a pinched separator
Manufacturer Defects
Celina Mikolajczak et. al, Lithium-Ion Batteries Hazard and Use Assessment, Exponent, July 2011
Separator Tears
Wrinkling
Cuts
Corrosion
Tolerances
Separator pinhole
Thermal Runaway● Starts at an imperfection in the separator (small hole, tear, dendrites).
● Internal short circuit occurs between the Cathode and Anode →
● High current flow → Higher internal cell temperature
● → Progressive destruction of the separator via melting
● Occasionally the melting seals the separator, stops the short circuit (more often in low charged cells)
● Otherwise a cascading energy release occurs
● Cell temperature > 700℃
When lithium batteries catch fire: How overcharging can do bad things to Li-ion cells, https://www.youtube.com/watch?v=YuKF8XfCVKQ
5.5v charge →
Remains analysis of unburnt cells
Celina Mikolajczak et. al, Lithium-Ion Batteries Hazard and Use Assessment, Exponent, July 2011
Celina Mikolajczak et. al, Lithium-Ion Batteries Hazard and Use Assessment, Exponent, July 2011
Variety of damage - All of these had been in a fire
Still good OKNot so good but still intact
Not so good!Internal Short → Fire most likely started in this cell
Internal examination helps determine origin likelihood
International StandardsUL 1642 - Safety of Lithium-Ion Batteries - Testing
UL 2580 - Batteries for use in electric vehicles
GB /T18287 - Chinese National Standard for Lithium Ion batteries for mobile phones
ISO 12405 - specifies test procedures for lithium-ion battery packs and systems, to be used in
electrically propelled road vehicles.
IEC 62660 - specifies performance testing for automobile traction lithium-ion cells and batteries
ANSI/ISA-TR12.13.01-1000 (R2013) - Flammability characteristics of combustible gases &
vapours
DNVGL-RP-0043 - Safety, Operation and Performance of Grid-Connected Energy Storage
Systems
ANSI/CAN/UL 9540 - Energy Storage Systems and Equipment
UL 9540A - Test method for evaluating thermal runaway fire propagation in Battery Energy
Storage Systems
NFPA 855 - Standard for the installation of stationary energy storage systems
UL 62133-3 - specifies requirements and tests for portable sealed secondary lithium cells and
batteries for Canada and the US
ANSI/CAN/UL 1973 - Standards for batteries for use in stationary, vehicle auxiliary power and
light electric rail applications
ANSI/CAN/UL 1974 - evaluation for repurposing batteries
ISO 6469 - Electrically propelled road vehicles
IEC 62485-6 - Safety requirements for secondary batteries and battery installations Part 6:
lithium-ion batteries for traction applications
IEC 61851 - Electric vehicle conductive charging system
ISO/FDIS 17409 - Electrically propelled road vehicles – connection to an external electric
power supply – safety requirements
SAE J2380 - Vibration testing of electric vehicle batteries
SAE J2929 - Safety standards for electric and hybrid vehicle propulsion battery systems
utilizing lithium-based rechargeable cells
SAE J2464 - Electric and hybrid electric vehicle rechargeable energy storage system (RESS)
safety and abuse testing
SAE J2289 - Electric-drive battery pack system: functional guidelines
IATA transportation regulations
Applies to all transportation of batteries on planes
UN 3090:Lithium batteries, Class 9
UN 3480:Lithium ion batteries, Class 9
Passengers may need to prove the capacity rating of spare batteries that are identified by security or check-in staff.
Australian standardsDR2 AS/NZS 5139:2019 was recently published for public comment
● Electrical installations — Safety of battery systems for use with power conversion equipment (Draft)
● Refers to an article called “Best Practice Guide: Battery Storage Equipment Electrical Safety Requirements” published July 2018
● Recommends what general electrical standards to refer to, provides a risk matrix
No other specific Lithium Ion battery standards!
Recommendations for consumers
Charging:
● Don’t charge a battery unsupervised if charging with a non-OEM charger, if leaving the house unplug it.
● For power tool batteries, don’t leave them sitting on the charger if they’re fully charged.
● Don’t charge a battery while it is hot (>40℃).
● Avoid cheap/non-genuine chargers for generic use.
● Slower charging (low current charging) of batteries is safer and also prolongs the life of the battery.
● Charging on non-flammable surfaces reduces fire damage risk.
● Don’t fully charge a battery before leaving it in long term storage. This degrades the performance over
time.
Recommendations for consumers
Battery Treatment:
● Low cost/no-name power banks, e-scooters, drones, hoverboards often skimp out on using
protection or good quality batteries. Be wary.
● Don’t leave your devices in a hot place, like inside a car during summer.
● Don’t carry loose Lithium Ion batteries. If possible transport them in a container for protection
against drops/external short circuits.
● Fireproof Lithium Ion bags also exist for fire protection
Typically for drone batteries which don’t include protection →
● Recycle your lithium ion battery devices from old devices.
○ More information here: https://recyclingnearyou.com.au/batteries/
Recommendations for regulators
● Make sure consumers are informed about the battery protections in their devices.
● Implement a standard to require the following protections:
→ Protection against excessive current or voltage when the battery is charged or discharged.
→ Internal protection against gas pressure build-up for cylindrical cells.
○ For replaceable cylindrical cells:■ PTC (excessive current cut-off)■ CID (excessive gas pressure cut-off)
○ Electronic protections for all varieties of Lithium Ion cells:■ Protection circuit for single cell devices■ BMS for multi cell devices with balance charging functionality
● Mandate warnings on devices with batteries and on Lithium Ion cells →
Recommendations for regulators
● For larger scale batteries (automotive, industrial, house batteries) the following aspects should be
investigated:○ Gas chemical/pressure detection for active fire protection○ Temperature monitoring of batteries○ Appropriate cooling of batteries○ Standard for physical protection of battery containers against fire
■ Container materials to prevent the spread of heat■ Ventilation consideration for removal of hazardous gases■ Use of low flammability materials, certified according to UL 94/ISO 11925-2
● Fireproof lithium ion bag testing standard; how ‘fireproof’ are lithium ion battery storage
products? Perhaps a similar rating system to IP ratings in IEC standard 60529.
● Public awareness on Lithium Ion battery recycling.
