AMPED SENSOR: Smart Embedded Network of

Sensors with Optical Readout

AMPED Meeting 2015, Chicago, IL

Project Team

Ajay Raghavan (PI), Peter Kiesel,

Anurag Ganguli, Julian Schwartz,

Andreas Schuh, Alex Hegyi, Bhaskar Saha

Mohamed Alamgir, Jeffrey West,

Paul Laurain, Robert Busser, Adnan Haider,

HoeJin Hah, ChaeAh Kim

www.parc.com/sensor

/Key Personnel

SENSOR Overview

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• Fiber-optic (FO) cell sensing, smart algorithms for BMS

• Low-cost, high-accuracy, field-able PARC readout

• LG Chem Power expertise for EV-grade technology

Cell State Sensing

with FO Sensors

3 www.parc.com/sensor

FO Sensor Example: Fiber Bragg Gratings

(FBGs)

• Can be selectively sensitive to various stimuli: Strain, temperature, chemical conc., current, voltage

• Multiplex-able for multiple sensors on single FO

• Hair-thin, light-weight, EMI-free, robust

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Photonic crystal sensor

Silicon micro-sphere sensor

Surface plasmon resonance sensor

Laser cavity sensor

Fiber Bragg grating sensor

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Early Study for External Strain, Temperature

λ2 (loose)

Readout

λ1 (fixed)

“Loose” external FBG picks temperature only

Cell-fin-cell setup mimics module pressure, cooling

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Mechanical Strain Across C Rates

Curves very similar across C rates, incl. dynamic cycles

Accurate SOC algorithms trained on few static cycles 6

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ignal (p

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ignal (p

m)

Intercalation Stages from FBG Strain Signal

• FBG derivative peaks match across C rates

• Useful for SOX estimation; stage shifts indicate aging

• Peaks of cell V signal derivative weaker, vary w/ C-rate

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From Sethuraman 2010

Graphite Stage 4 Stage 3 Stage 2 Stage 1

FBG derivative peaks Ξ

intercalation stage transitions

SOC (%)

External FBG: Preliminary Comparison w/

Electrical Strain Gage, NTC Signals

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FB

G s

ign

al (p

m)

FO

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Str

ain

gage s

ignal (με)

Time (hours)

FO

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nal (p

m)

NT

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ignal (o

C)

Time (hours)

No load CC Charge CV No load

“Loose” FBG v/s NTC thermistor FBG strain v/s electrical strain gage

Electrical strain gage signals seem not as repeatable

NTC signal shows tendency to pick up EMI

Pouch Cells w/ Internally Embedded FO

Stable embedded config w/ FBGs bonded to electrode

Approach extended to large-format cells 9

15 Ah large-format

1.5 Ah small-format

Internal Small-Format Cell FBG Signals Internal FBG signal FBG T signal

Internal signals 2-5x stronger than external, repeatable

Cell internal temp., other useful SOX features detectable

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ignal (p

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Internal FBG Robustness: Dynamic Cycles

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Internal more robust than external; both better than cell V

2.5% SOC or better achieved in dynamic cycles

SOH with Internal FBG Signals: Early Results

• Experimental chemistry: cell life ~100 cycles

• Steady increase in base FBG wavelength over life

10-cycle look-ahead capacity prediction error of <1.8%!

Also possible to detect subtle overcharge, failures 12

Time (hrs)0 50 100 150 200 250 300 350 400 450 500

Com

pensate

d s

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Cycle number0 10 20 30 40 50 60 70

Cell c

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uring d

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0.97

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0.99

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1.01

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Cycle number

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Ah)

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Time (hours) Discharge cell capacity (Ah)0.97 0.98 0.99 1 1.01 1.02 1.03 1.04

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Discharge cell capacity (Ah)0.97 0.98 0.99 1 1.01 1.02 1.03 1.04

Volta

ge (

V)

4.336

4.338

4.34

4.342

4.344

4.346

4.348

4.35

Discharge cell capacity (Ah) Discharge cell capacity (Ah) V

oltage (

V)

FB

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at end o

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FBG base λ (pm) Rest cell V:

Change within BMS

voltage accuracy

Results towards xEV Pack

Field Deployment

13 www.parc.com/sensor

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Functional Cells w/ Embedded FO

Cell performance unaffected by FO sensors (30+ cells)

FO sensors with certain coatings unaffected in electrolyte

Experimental cell capacity

w/ cycling

Signal drift in long-term

stability test

-60

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0 10 20 30 40 50

Wavelen

gthshi(pm)

Time(weeks)

FBGsignal +3degC -3degC

PARC’s Low-Cost Multiplexed FO Readout

• 10 fm accuracy (~0.01 με), up to 1000 channels

• 3-7% pack cost feasible for SENSOR system

• xEV vibration robustness demo’ed (200 fm or better)

SENSOR can replace BMS electrical sensing

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Prototype size:

8” x 4.5” x 4”

Prod. size:

3.5” x 3” x 0.7” C/2 charge cell FBG

signal w/ new readout

External FO 2011 Volt

1 of || strings monitored

Savings: $856+ 8.3 lbs.

Cost: $294+ 0.2 lbs.

Net: $562 + 8.1 lbs.

Internal FO 2011 Volt

All cells w/ embedded FO

Savings: $1134+ 19.2 lbs.

Cost: $333 + 0.2 lbs.

Net: $801 + 18.9 lbs.

Costs comparable; internal can offer more oversizing trim

Low added $ for more sensors; more value w/ big packs

Fewercells$100

Vharness$90

isensor$28

HighVsensor$10

Tsensor$19

Isola on$204

BMSboards$354

Electronicsrecycling

$7

Lightweight$29

Coolantsensor$15

Ext. v/s Int. FO Sensing Value: 2011 Volt

Fewercells$328

Vharness$90

isensor$28

HighVsensor$10

Tsensor$19

Isola on$204

BMSboards$354

Electronicsrecycling

$7

Lightweight$67

Coolantsensor$28

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Ongoing Validation, Module-Level Tests

• Presently 4-cell module; larger module test w/ OEM

• Modest training, more testing: xEV dynamic, T-tests

• For internal FBGs: similar SOC tests, plus stress tests

• Also instrumenting in PARC e-Bike fleet Li-ion packs

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Dynamic discharge

AMPED Attendees’ Pooled BMS Challenges

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SENSOR project addresses 40% of attendee-BMS issues

Summary and Concluding Remarks Exciting results for BMS sensing, cell state challenges:

• FO new BMS sensing mode for cell state, aging

• Promising cell-level results: 2.5% accurate SOX

• Shown path to field deployment with PARC readout

• Cost-perf. model indicates pack trim w/ simpler BMS

In OEM discussions for further validation, tech transfer

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Fewercells$328

Vharness$90

isensor$28

HighVsensor$10

Tsensor$19

Isola on$204

BMSboards$354

Electronicsrecycling

$7

Lightweight$67

Coolantsensor$28

wavelength

reflection

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wavelength

reflection

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reflection

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light

gain medium

fluidic

channel

mirror

n2

n1

wavelength

outp

ut

inte

nsity

wavelength

outp

ut

inte

nsity

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light

λ1

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reflection λ1 λ1+Δλ

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wavelength

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wavelength

reflection λ1 λ1+Δλ

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Photonic crystal sensor

Silicon micro-sphere sensor

Surface plasmon resonance sensor

Laser cavity sensor

Fiber Bragg grating sensor

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lightContact: raghavan@parc.com