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LG Fuel Cell Systems Program and Technology Update
2015 SOFC Workshop, 14 July 2015Zhien Liu and Cris DeBellis
LG data
Outline 200kW scale demonstration test Cell degradation understanding and mitigation
Primary sources of degradation Improvements for entrance-into-service (EIS) technology
Optimization of LSM-based cathode Single layer anode
Lower ASR cell technology Broad changes of active layers and design for near-
term product Evaluating nickelate cathodes for longer-term
objective
LG data
LG Fuel Cell System Inc. 3
Building on a Solid Foundation
LG data
LGFCS Integrated String Test (IST)
Testing began June 2015 Pipeline natural gas to grid connection 200kW-class pressurized SOFC system Demonstrates functionality of integrated
subsystems: Fuel processing Pressurized SOFC vessel Turbogenerator assembly Power electronics Controls and safety system
Utilizes cell technology developed under LGFCS DOE SECA programs
LG data
Block Performance Testing Prior to the IST UK test rig modified to test block design of IST
Rig accommodates 1 to 3 blocks Design point ASR of 0.32 ohm-cm2 at block midpoint 860C demonstrated
Epsilon technology was frozen in 2012 for IST test Lower degradation at low end temperature of block operation Cathode degradation is dominant at high end temperature of block
operation Current status: 13.5 mohm-cm2/1000 hr across block temperatures
(Power deg: 0.55%/1000 h)ASR change:11.0 mohm-cm2/1000 h
(Power deg: 1.18%/1000 h)ASR change:16.1 mohm-cm2/1000 h
LG data
Key Degradation Mechanisms for Cathode
Free MnOx formation and accumulation Cathode densification Chromium contamination Second phase formation was identified near
electrolyte interface after high temperature operation
Three revised LSM-based cathode formulations under evaluation for improved durability
10
LG data
Free MnOx distribution for Epsilon LSM cathodes Mn/La ratio in bulk cathode showed constant level as a
function of operation time. Mn/La ratio at cathode/electrolyte interface increases with time.
11
•Bulk cathode •Cath/Ele interface
Mn/La ratio from EDS analysis
LG data
EIS Cathode Shows Less MnOx Rich Near Cathode/Electrolyte Interface
12
•Cath/Ele interface
EIS cathode has low and stable Mn content near cathode /electrolyte interface up to 8,000 hrs of operation
LG data
0.10
0.15
0.20
0.25
0.30
0.35
0 200 400 600 800 1000
ASR
s, Ω
-cm
2
Elapsed Time, hours
Cell ASR - SCT6-149_4x
A1: Ep cathodeA2: EIS1 cathodeB2: EIS2 cathodeB1: EIS3(U) cathode
10% O2 - wet
Anode: bundle inlet fuel
EIS2
Epsilon EIS1
EIS3
EIS Cathode Demonstrated Improved Resistance against Densification during Operation
Footer
At normal operating conditions, densification starts to show up at 8,000 hrs Under accelerated testing conditions, initial densification of epsilon
cathode was observed at 500 hrs. Selected EIS cathode shows more microstructural stability.
Accelerated Test Conditions
LG data
PCT208B2: tested at 925oC for 11,500hr
Second Phase Identified in LSM Cathodes Near Electrolyte Interface
Second phase formed near cathode/electrolyte interface after long term operation at 925oC
La-Zr rich phase No La-rich phase at 800oC Maximum block temperature to be
reduced with in-block reforming
14
PCT89B: 800oC/16,000hr
Epsilon
Epsilon EIS1
•Ele
ctro
lyte
•[PCT189A2]
•La-rich
•Mn-rich
•Mn•LSM
•La
•Zr (YSZ)
PCT189A2: tested at 925oC for 16,000hr
Epsilon
LG data
Understanding Cr Effect on Cathode Performance is One of Key Activities
15
More Cr deposition at cath/Ele interface in strip 1 (inlet) of block testing Cr deposition in bulk cathode and CCC shows no trend vs position Accelerated button cell test to understand Cr effect
Inlet Outlet
Button cell set-up for Cr test
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.10
0 200 400 600 800 1000 1200
Tota
l Rp
(AN
+ C
A) /o
hm-c
m^2
Time (hr)
Ep cathode witout Cr EIS1 without CrEIS2 without Cr EIS1 with CrEIS2 with Cr EIS3 with Cr
w/o Cr source
w/ Cr source
T1314(3,000 hrs)
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.10
0 200 400 600 800 1000 1200
Tota
l Rs /
ohm
-cm
^2
Time (hr)
Ep cathode witout Cr EIS1 without CrEIS2 without Cr EIS1 with CrEIS2 with Cr EIS3 with Cr
w/o Cr
w/ Cr
Epsilon
LG data
Only change from epsilon cell technology was the cathode and PIC material
Average bundle degradation rate at 860oC: 6.0 mohm-cm2/1000 hrs Projects to a 3.0 year life across block temp.
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0 2000 4000 6000 8000 10000
ASR
, ohm
-cm
2
Elapsed Time, hours
Bundle ASR: ATBT3/6 - Cathode Study Triple Bundle Test
Accelerated Anode Testing Helps Database and Decision Making Current density, temperature, and fuel utilization Accelerated testing confirmed single layer anode is more stable than
epsilon plus anode
18
Single layer anodeEpsilon plus anode
AnodeCathode
LG data
Redox Tolerant Anode Benefits System Operation Epsilon plus anode is able to tolerate 4-5 redox cycles Single layer anode being developed for improved redox tolerance
Equivalent or better than epsilon bi-layer structure Able to tolerate more redox cycles without significant ASR change
20Lower ASR Technology was Demonstrated in Block Level High conductive interconnect plus EIS cathode Average block ASR: 0.28 ohm-cm2 vs 0.35 ohm-cm2 for epsilon
technology Stable performance in 700 hrs of operation with 15.7 kW output
EpsilonEpsilon
Improved PIC & cathode
Improved PIC & cathode
860oC
0.05
LG data
0.15
0.20
0.25
0.30
0.35
0.40
0.45
0.50
760 780 800 820 840 860 880 900 920
PTT-Epsilon technologyPTT6: Low ASR PIC+EIS cathode+Thin wall tubePoly. (Low ASR PIC)
RU A
SR ,
Ω
Temperature,
4 Bara, system conditions
Pressurized full tube testing
Further ASR Reduction - Thin Wall Tube Thin wall tube could reduce fuel diffusion resistance
ASR reduction 0.02 to 0.03 ohm-cm2 by subscale cell Feasibility was demonstrated by pressurized full tube test
Case Western Reserve University University of South Carolina
LG data
Acknowledgements_Continued This material is based upon work supported by the U.S. Department
of Energy, National Energy Technology Laboratory under Award Number DE-FE0012077 and DE-FE0023337.
Disclaimer: This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of the authors expressed herein do not necessarily state or reflect those of the United States Government of any agency thereof.