Lithium & Safety webinar - ARTS Energy...Lithium & Safety webinar July 2nd, 2019 Different cell...

Lithium & Safety webinar

July 2nd, 2019

Different cell types

2 ARTS ENERGY - CONFIDENTIAL & PROPRIETARY July 2nd, 2019

Types

Cylindrical Prismatic Pouch

Which failures?

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July 2nd, 2019

ARTS ENERGY - CONFIDENTIAL & PROPRIETARY

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What are the risks?

July 2nd, 2019

Risks

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Risks are :

Gaz emission

Smoke

Fire

Explosion

Possible causes :

over–temperature / over charge / over courant / internal short circuit, crush or

perforation

That leads to temperature increase

That leads to thermal runaway

ARTS ENERGY - CONFIDENTIAL & PROPRIETARY July 2nd, 2019

Why Thermal Runaway propagation is dangerous ?

A lithium cell can have an internal short-circuit like a nickel based cell. But with lithium technology, this internal short-circuit can be very dangerous.

If 1 cell have an internal short circuit, it’s not very sensible, but if this cell propagates to other battery cells we will have a Thermal Runaway Propagation. This phenomena can be very dangerous:

20 X =

Thermal Runaway


Safety mechanism


160°C-200°C

120°C-130°C

75°C-100°C

70°C

60°C

Gaz emission (CO2)

Gaz emission (O2)

Electrolyte ignition

Temperature

CID Opening

Vent Opening

Charge interruption

Discharge interruption

Current interruption

Gaz emission

Separator melting

450°C

Charge stopped

Discharge stopped

Current interruption

Fire/ explosion

Protections Effects

Irre

vers

ible

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At cell level

July 2nd, 2019

Safety component on cylindrical clls


PTC (Polyswitch)

On some energy cells, a PTC is inserted between the

CID and the lid (top). In case of over current, the PTC

goes into high impedance mode; which has the effect

of reducing the current.

CID (Current Interrupt device)

In case of inappropriate use such as overload, the

pressure increases and the CID deforms. Following

this deformation, the connection between the cathode

and the CID is interrupted and the current no longer

flows.

Security event

If the pressure continues to increase after opening the

CID, the vent opens to prevent explosion. Then the

gases escape to the outside in a safe way.

Safety component on pouch and prismatic

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Prismatic cell

No TPC or CID.

Presence only of a vent.

This is why it is recommended to insert a PTC or a thermo fuse at the

battery level in this case.

Polymer cell

No PTCs, IDCs, or vent.

In case of pressure, the cell will inflate and take a form of rugby ball, the

cell can even, in some cases, eventually catch fire or explode.

Hence the addition of protection at the battery level (PTC, Thermo fuse,

fuse, ...)


Difference between Li-Ion (Co,NMC,NCA,...) & LiFePO4

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Better thermal stability of cathod in LiFePO4

No O² generation => no thermal runaway

However, graphite anode same as Li-Ion Risk is still existing

PCM is needed


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At Electronic level

July 2nd, 2019

Lithium Ion must be managed cautiously!


Event •Over charge

•Over temperature

•External short circuit

•Over current

•Cell Internal short circuit

Run away start

•Temperature increase •Internal pressure increase

Effect • Fire

•Toxic or harmful gas escaping the battery (CO, organic electrolyte)

•Toxic or harmful liquids flowing out of the battery electrolyte, others)

•parts ejections from the battery

•Explosion

Protection Circuit

Mandatory into

battery pack

To keep voltage and current levels to secured levels and manage temperature, especially in charge

At hardware and software levels


Hardware application level

Thermal cut-off?

Fuse for current

Software Application level

Voltage management

Temperature management

Current management

Battery level

Overcharge Overdischarge Overcurrent Short circuit Thermal cut

off?

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At pack design level

July 2nd, 2019

It is a matter of Probability!

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July 2nd, 2019


To improve our knowhow, AE had invested in:

Thermal camera Thermal analysis Software

Cabin to realize abusive test

Internal equipment and first results

17 July 2nd, 2019 ARTS ENERGY - CONFIDENTIAL & PROPRIETARY

Results and Design factors

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Depends on cell technologies

Design impacts

July 2nd, 2019

Technologies Impact Conclusion

Nickel Cobalt Aluminum Very sensitive Must have safety design

Nickel Manganese Cobalt Sensitive Security levels must be adjust (capacity Vs power)

Lithium Phosphate Fer Safe No safety design is necessary


Factors with strong impact General impacts

Management of gas evacuation (Keeping « free » positive side of cell/ protecting of rejection/ Evacuating gas )

Take care with a sealed casing

Isolation of TR cell with fuse connection Design impact

Space between cells => Small design impact


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If we are in the “Internal cell failures” case:

With Japan / Korean suppliers => 1 to 5 ppm with a particle => Hypo 2 ppm

With Chinese suppliers => 10 to 150 ppm with particle => Hypo 50 ppm

This will happen during charge!


Battery configuration

Battery pack Probability of failure (2 ppm)

Battery pack Probability of failure (50 ppm)

2 cells 1/ 250 000 1/ 10 000

8 cells (4S2P) 1/ 62 500 1/ 2 500

39 cells (13S3P) 1/ 12 800 1/ 510

98 cells (7S14P) 1/ 5 100 1/ 200


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Depending on customer case…


+ -

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Conclusion

July 2nd, 2019

0 risk is not possible ! Only reducing risk!

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Respect the recommendations of the cell manufacturers

Voltage thresholds for overcharge, over discharge

Temperatures in charge and discharge

Acceptable currents

Prohibition of cold or hot load

Develop following methods that integrate risk management (EN61508, EN ISO 13849-1, IEC62061, ...)

Define with customer what are acceptable risks through their safety analysis

Design to avoid the spread of a failure

Run away test as a validation


ARTS Energy support


Electrical safety

Voltage protection level in accordance with cell manufacturers (design)

Current protection in accordance with cell manufacturers and application (design)

Short circuit protection in accordance with battery impedance (design)

Thermal run away propagation management

Mechanical & Electrical arrangements based on our tests (design)

Case vent dimensioning (design)

Validation of final product (test)

Thank you for your

attention

www.arts-energy.com

[email protected]

Our Head Office / Manufacturing Site


ARTS Energy SAS

10 Rue Ampère

Zone industrielle

F-16440 Nersac

Tel. : +33 (0)5 45 90 35 52 / 53

Fax. : +33 (0)5 45 90 37 68

24 July 2nd, 2019

http://www.arts-energy.com/





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Lithium & Safety webinar - ARTS Energy...Lithium & Safety webinar July 2nd, 2019 Different cell...

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