Download - Battery Ajay Raghavan
SENSOR*: Embedded Fiber-Optic (FO)
Sensing for Battery Packs
*SENSOR: Smart Embedded Network of Sensors with an Optical Readout
www.parc.com/sensor
Dr. Ajay Raghavan
[email protected] | 1-650-812-4724
ARPA-E AMPED Program
2
AMPED: Advanced Management and Protection of Energy Storage Devices
SENSOR Overview
3
Online at www.parc.com/sensor
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FO Sensor Example: Fiber Bragg Gratings
(FBGs)
wavelength
reflection
white
light
wavelength
reflection
wavelength
reflection
white
light
gain medium
fluidic
channel
mirror
n2
n1
wavelength
outp
ut
inte
nsity
wavelength
outp
ut
inte
nsity
white
light
λ1
wavelength
reflection λ1 λ1+Δλ
stimulus
white
light
λ1
wavelength
reflection λ1 λ1+Δλ
wavelength
reflection λ1 λ1+Δλ
stimulus
λ1white
light
wavelength
reflection λ1 λ1+Δλ
stimulus
λ1white
light
wavelength
reflection λ1 λ1+Δλ
wavelength
reflection λ1 λ1+Δλ
stimulus
Photonic crystal sensor
Silicon micro-sphere sensor
Surface plasmon resonance sensor
Laser cavity sensor
Fiber Bragg grating sensor
wavelength
transm
issio
n
white
lightwavelength
transm
issio
n
wavelength
transm
issio
n
white
light
5
Strain, temperature, gas,
chemical, current, voltage, ...
Multiplexable: multiple
sensors on single FO
Initial Study for External Strain, Temperature
λ2 (loose)
Readout
λ1 (fixed)
6
Picks up only
thermal strain
Picks up
total strain
Setup mimics
module pressure,
cooling
Mechanical Strain Across C Rates
7
FB
G s
ignal (p
m)
FB
G s
ignal (p
m)
FB
G s
ignal (p
m)
Curves similar across C rates, including dynamic cycles
Intercalation Stages from FBG Strain SignalF
BG
sig
na
l derivative (
pm
/s)
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SOC (%)
From Sethuraman et al. 2010
Graphite Stage 4 Stage 3 Stage 2 Stage 1
FBG derivative peaks intercalation stage transitions
Stage transitions shift
w/ life: aging metric
From Liu, P. et al. 2010
Peaks aligned
across C-rates
Cold Test at –15.5oC
Strong, accurate FBG signal even at cold temperatures9
C/10 to cell V limit
C/2 to cell V limit
~50% SoC at end of charge
accurately sensed by FBG
Electrical v/s FBG: Cell External Sensing
10
FB
G s
ignal (p
m)
FO
sig
na
l (p
m)
Str
ain
ga
ug
e s
ign
al (μ
ε)Time (hours)
FO
sig
na
l (p
m)
NT
C s
ign
al (o
C)
Time (hours)
No load CC Charge CV No load
“Loose” FBG v/s NTC thermistorFBG strain v/s electrical strain gauge
Electrical strain gauge signals seem not as repeatable
NTC signal shows tendency to pick up EMI
Pouch Cells with Internally Embedded FO
Stable embedded config w/ FBGs bonded to electrode
Approach extended to large-format cells 11
15 Ah large-format
1.5 Ah small-format
Internal Small-Format Cell FBG SignalsInternal FBG signalFBG T signal
Internal signals 2-5x stronger than external
Cell internal temperature, other SOX features detectable
FB
G s
ign
al (p
m)
Time (h)
12
Internal FBG Robustness: Dynamic Cycles
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Internal more robust than external; both better than cell V
4-Cell Module Assembly w/ Large FO-Cells
No major module assembly line changes for FO-cells
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Optical
fibers
Connectors for cooling fins
Individual
15 Ah cell
HPPC Response at 50% SOC, 20oC
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7C for 10s
“The ideal HPPC response”
- Major OEM battery engineers
60s rest 5C for 10s
Strain changes linearly over pulse, settles
60s rest
FBG Strain Signals: Rapid Dynamic CyclesUS06
Ce
ll #
1C
ell
#3
UDDS
Red: US06 cycles
Blue: Static cycles
Red: UDDS cycles
Blue: Static cycles
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Error of <2.5% over 5-100% SOC achieved: >2x SOTA
Initial Aggressive Cycle SOH Results
10-cycle horizon capacity prediction error of <2.2%
Number of cycles0 50 100 150
Com
pe
nsate
d s
tra
in (
pm
)
100
120
140
160
180
200
220ObservedModel
Prediction horizon Mean error Max error
1 cycle ahead 0.14% 0.38%
5 cycles ahead 0.24% 1.1%
10 cycles ahead 0.4% 2.2%
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Charge capacity (Ah)14.8 14.9 15 15.1 15.2
Com
pen
sa
ted s
train
0.1
0.12
0.14
0.16
0.18
0.2
0.22
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FO-Embedded Cells: xEV-Grade Life, Seal
Electrolyte-robust FO coatings
-60
-40
-20
0
20
40
60
0 10 20 30 40 50
Wavelen
gthshi(pm)
Time(weeks)
FBGsignal +3degC -3degC
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12.5
13
13.5
14
14.5
15
15.5
16
0 50 100 150
DischargeCap
acity(Ah)
Cycle#
BaseCell
Fiber-op ccell
25⁰CDisharge:30ACharge:15A1C 25⁰C
Disharge:30ACharge:30A2C
Projected FO-cell life: 1100+ cycles
FO-pouch seal
integrity as good as
pouches w/o FO in
60oC, 95% RH test
Only electrolyte
(Without Cell)
FO
And One More Thing… PARC’s FO Readout
SENSOR can replace BMS electrical sensing
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From Thylen and Wosinski 2011Prototype size:
8” x 4.5” x 4”
Anticipated
production size:
3.5” x 3” x 0.7”
~$300 for high-vol. system
Drop to $150 feasible
50 fm (0.05 με) res.: 20x SOTA
Up to 480 channels at 40 Hz
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 more SOX accuracy, value
Low added $ for more sensors; more value w/ larger 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 Value: Chevy Volt Example
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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SummaryExciting results for BMS sensing, cell state challenges:
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
reflectio
n
white
light
wavelength
reflectio
n
wavelength
reflectio
n
white
light
gain medium
fluidic
channel
mirror
n2
n1
wavelength
outp
ut
inte
nsity
wavelength
outp
ut
inte
nsity
white
light
λ1
wavelength
reflectio
n λ1 λ1+Δλ
stimulus
white
light
λ1
wavelength
reflectio
n λ1 λ1+Δλ
wavelength
reflectio
n λ1 λ1+Δλ
stimulus
λ1white
light
wavelength
reflectio
n λ1 λ1+Δλ
stimulus
λ1white
light
wavelength
reflectio
n λ1 λ1+Δλ
wavelength
reflectio
n λ1 λ1+Δλ
stimulus
Photonic crystal sensor
Silicon micro-sphere sensor
Surface plasmon resonance sensor
Laser cavity sensor
Fiber Bragg grating sensor
wavelength
tra
nsm
issio
n
white
lightwavelength
tra
nsm
issio
n
wavelength
tra
nsm
issio
n
white
light
[email protected]; Booth #1954
FO: a new BMS enabler
<2.5% accurate SOX: >2x SOTA
Practical for xEV field deployment
$-cost competitive
Red: US06 cycles
Blue: Static cycles
SENSOR Cost Est.: ’11 Volt “Ext.” v. “Internal”
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External Config 1 of
||Cost Estimate:
$303 (1M xEVs/year)
$366 (200k xEVs/year)
Internal Strain + Temp. all
cells Configuration Cost
Estimate:
$352 (1M xEVs/year)
$572 (200k xEVs/year)Cost estimates incl. assembly, on solid footing w/ new dataReadout key cost: low cost Δ to embed/sense more cells
Lightsource$10
FOsensors$34
Readout$250
Moduleconnect
$8
Recyclingfee$3
FOcellembedding
$6Controls$14
Power$1
Tech.premium
$26
Lightsource$10
FOsensors$13
Readout$250
Moduleconnect
$8
Recyclingfee$3
Controls$5
Power$1
May contain trade secrets or commercial or financial information that is privileged or confidential and exempt from public disclosure.
May contain trade secrets or commercial or financial information that is privileged or confidential and exempt from public disclosure.
New BMS Scenarios w/ SENSOR: Summary
1. xEV dynamic cycle utilization not limited by cell V
2. BMS control to maximize life w/ better cell state info:
► Detect, manage early incipient issues, excessive strain
► Track intercalation stage shifts for cell aging estimate
► Minimize temp. differential between internal/external
3. More informed charging, regen, balancing
4. Better cell utilization for cold temp. use: avoid
polarization issues in cell V
5. Enhanced safety from awareness of incipient failure
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Broad range of new use cases anticipated to enable
better BMS for longer life and pack utilization to true limitsMay contain trade secrets or commercial or financial information that is privileged or confidential and exempt from public disclosure.
May contain trade secrets or commercial or financial information that is privileged or confidential and exempt from public disclosure.
Applicable to Other Chemistries: LiFePO4
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Considerable external FBG strain signal, features
also seen in flat-voltage chemistry like LFP
Time (h)
FB
G s
ign
al (p
m)
Vo
lta
ge
(V
)
Cu
rre
nt (A
)
Ext. FBG Strain for Over-V (AA PP Pouch Cell)
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Sample point
Volta
ge (V
)C
urr
ent (m
A)
FB
G s
ignal (n
m)
V limit (4.2 V)
Clear FO strain signal change right after 1st mild overcharge
After 1st over-
V
Residual Strain Effect on Cell Performance
Residual cell strain after cycles affects performance
Cell performance and strain curves (from Wang et al., JECS ’04, ’07)
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Cell Internal Temperature: Higher C Rates
Worse (20oC) at higher C rates and large-format cells
(a) Internal 4.4 Ah LiFePO4 cell temp: 5oC, 16 C pulses, cooled;
(a)
(b)
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(b) Persistent SOC difference (from Fleckenstein et al. JPS ‘11)
Use Case #2: Control to Maximize Cell Life
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(b) 4.4 Ah LiFePO4 cell temp.: 5oC, 16 C,
cooled (Fleckenstein et al. JPS ‘11)
(c) Better SOH, capacity fade
prediction to manage cell life
(a) FBG sensors useful for detecting
excess cell strain (can lead to
electrode cracking)
SENSOR-enabled better real-time cell state awareness for
BMS to manage for longer pack life
Discharge cell capacity (Ah)0.97 0.98 0.99 1 1.01 1.02 1.03 1.04
Str
ain
at e
nd o
f cha
rge
(pm
)20
30
40
50
60
70
80
90
100
110
Discharge cell capacity (Ah)0.97 0.98 0.99 1 1.01 1.02 1.03 1.04
Vol
tage
(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)
Vo
lta
ge
(V
)
FB
G s
tra
in a
t e
nd
of ch
arg
e (
pm
)
Use Case #5: Enhanced Safety
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SENSOR can detect subtle failures not seen in cell V/i signals
• LCO cells fatigued under
rapid dynamic cycles
• Cell failure seen much
later in cell V (plating)
Electrical signals FBG signals and SOC
Drop in SENSOR
signal despite
expected flat SOC
from i-counting