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A High Temperature (400 to 650oC) Secondary Storage Battery Based on Liquid Sodium and Potassium Anodes

08 Jun 2007-
TL;DR: In this paper, a planar high temperature rechargeable battery based on an alkali metal ion conducting, highly refractory, beta '' alumina solid electrolyte (BASE) sandwiched between liquid sodium (or potassium) anode and liquid metal salt cathode was successfully demonstrated at a working temperature as high as 600 C.
Abstract: This STTR Phase I research program was on the development of high temperature (400 to 650 C), secondary batteries with roundtrip efficiency > 90% for integration with a 3 to 10 kW solid oxide fuel cell (SOFC) system In fulfillment of this objective, advanced planar high temperature rechargeable batteries, comprised of an alkali metal ion conducting, highly refractory, beta'' alumina solid electrolyte (BASE) sandwiched between liquid sodium (or potassium) anode and liquid metal salt cathode, were developed at MSRI The batteries have been successfully demonstrated at a working temperature as high as 600 C To our knowledge, so far no work has been reported in the literature on planar rechargeable batteries based on BASE, and results obtained in Phase I for the very first time demonstrated the viability of planar batteries, though relatively low temperature tubular-based sodium-sulfur batteries and ZEBRA batteries have been actively developed by very limited non US companies The results of this Phase I work have fulfilled all the goals and stated objectives, and the achievements showed much promise for further, substantial improvements in battery design and performance The important results of Phase I are briefly described in what follows: (1) Both Na-BASE and K-BASE discs and tubes have been successfully fabricated using MSRI's patented vapor phase process Ionic conductivity measurements showed that Na-BASE had higher ionic conductivity than K-BASE, consistence with the literature At 500 C, Na-BASE conductivity is 036 S/cm, which is more than 20 times higher than 8YSZ electrolyte used for SOFC at 800 C The activation energy is 2258 kJ/mol (2) CuCl{sub 2}, FeCl{sub 2}, ZnCl{sub 2}, and AgCl were identified as suitable salts for Na/metal salt or K/metal salt electrochemical couples based on thermochemical data Further open circuit voltage measurements matched those deduced from the thermochemical data (3) Tubular cells with CuCl{sub 2} as the cathode and Na as the anode were constructed However, it was discovered that CuCl{sub 2} was somewhat corrosive and dissolved iron, an element of the cathode compartment Since protective coating technology was beyond this Phase I work scope, no further work on the CuCl{sub 2} cathode was pursued in Phase I Notwithstanding, due to its very high OCV and high specific energy, CuCl{sub 2} cathode is a very attractive possibility for a battery capable of delivering higher specific energy with higher voltage Further investigation of the Na-CuCl{sub 2} battery can be done by using suitable metal coating technologies developed at MSRI for high temperature applications (4) In Phase I, FeCl{sub 2} and ZnCl{sub 2} were finalized as the potential cathodes for Na-metal salt batteries for delivering high specific energies Planar Na-FeCl{sub 2} and Na-ZnCl{sub 2} cells were designed, constructed, and tested between 350 and 600 C Investigation of charge/discharge characteristics showed they were the most promising batteries Charge/discharge cycles were performed as many as 27 times, and charge/discharge current was as high as 500 mA No failure was detected after 50 hours testing (5) Three-cell planar stacks were designed, constructed, and evaluated Preliminary tests showed further investigation was needed for optimization (6) Freeze-thaw survival was remarkably good for planar BASE discs fabricated by MSRI's patented vapor phase process

Summary (1 min read)

EXECUTIVE SUMMARY

  • This STTR Phase I research program was on the development of high temperature (400 to 650oC), secondary batteries with roundtrip efficiency > 90% for integration with a 3 to 10 kW solid oxide fuel cell (SOFC) system.
  • To their knowledge, so far no work has been reported in the literature on planar rechargeable batteries based on BASE, and results obtained in Phase I for the very first time demonstrated the viability of planar batteries, though relatively low temperature tubular-based sodium-sulfur batteries and ZEBRA batteries have been actively developed by very limited non U.S. companies.
  • The important results of Phase I are briefly described in what follows: 1. Both Na-BASE and K-BASE discs and tubes have been successfully fabricated using MSRI’s patented vapor phase process.
  • Further investigation of the Na-CuCl2 battery can be done by using suitable metal coating technologies developed at MSRI for high temperature applications.
  • Charge/discharge cycles were performed as many as 27 times, and charge/discharge current was as high as 500 mA.

Technical Objectives of the Proposed Work (Phase I)

  • Technical objectives of the proposed work for this STTR Phase I, as given in the proposal, are given in what follows: 1. To fabricate Na-BASE and K-BASE discs and tubes of high ionic conductivity, high strength, and excellent resistance to moisture attack using a patented, vapor phase process.
  • The following materials for the construction of batteries have been used and demonstrated successfully in Phase I: Electrode compartment: Materials for the construction of electrode compartments must sustain moderately high temperatures and somewhat corrosive atmospheres.
  • The prospective cathode material, identified in the Task 1, along with a stainless steel felt was placed inside the tube surrounding the BASE tube.
  • Since the eutectic melting temperatures of NaCl and the metal salts listed in Table 1 were quite low (< 400oC), this impregnation method worked very well compared to other approaches, such as hot pressing powders or co-sintering powder mixtures.
  • At 500oC, tests of charge/discharge cycle were carried out at a constant current 104 mA.

Summary/Conclusion

  • Phase I project was successfully completed on schedule, and all of the principal objectives in the proposed Phase I work were met to a very high degree.
  • Impedance measurements showed that Na-BASE had higher ionic conductivity than K-BASE.
  • Charge/discharge characteristic tests showed that both FeCl2 and ZnCl2 were favorable cathodes.
  • Charge/discharge cycles were performed as many as 27 times, and charge/discharge current was as high as 500 mA.
  • No failure was detected after 50 hours testing.

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Figures (34)

Content maybe subject to copyright    Report

Final Report
On the Project Entitled
A High Temperature (400 to 650
o
C) Secondary Storage Battery Based on
Liquid Sodium and Potassium Anodes
Sponsored by
U.S. Department of Energy, Contract No. DE-FG02-06ER86280
Submitted to:
Project Manager: Heather Quedenfeld
NETL-FE/
U.S. Department of Energy
3610 Collins Ferry Road, P.O. Box 880
Morgantown, WV 26507-0880
Submitted by
Dr. Greg Tao (Principal Investigator)
Materials and Systems Research, Inc.
5395 West 700 South
Salt Lake City, UT 84104
Phone: (801) 530-4987
FAX: (801) 530-4820
Effective Date of Contract: June 28, 2006
Contract Expiration Date:
March 27, 2007, Reporting Period: 06/28/2006 – 03/27/2007
June 8, 2007

2 of 34
EXECUTIVE SUMMARY
This STTR Phase I research program was on the development of high temperature (400 to
650
o
C), secondary batteries with roundtrip efficiency > 90% for integration with a 3 to 10 kW
solid oxide fuel cell (SOFC) system. In fulfillment of this objective, advanced planar high
temperature rechargeable batteries, comprised of an alkali metal ion conducting, highly
refractory, beta” alumina solid electrolyte (BASE) sandwiched between liquid sodium (or
potassium) anode and liquid metal salt cathode, were developed at MSRI. The batteries have
been successfully demonstrated at a working temperature as high as 600
o
C. To our knowledge,
so far no work has been reported in the literature on planar rechargeable batteries based on
BASE, and results obtained in Phase I for the very first time demonstrated the viability of planar
batteries, though relatively low temperature tubular-based sodium-sulfur batteries and ZEBRA
batteries have been actively developed by very limited non U.S. companies. The results of this
Phase I work have fulfilled all the goals and stated objectives, and the achievements showed
much promise for further, substantial improvements in battery design and performance.
The important results of Phase I are briefly described in what follows:
1. Both Na-BASE and K-BASE discs and tubes have been successfully fabricated using
MSRI’s patented vapor phase process. Ionic conductivity measurements showed that Na-
BASE had higher ionic conductivity than K-BASE, consistence with the literature. At
500
o
C, Na-BASE conductivity is 0.36 S/cm, which is more than 20 times higher than
8YSZ electrolyte used for SOFC at 800
o
C. The activation energy is 22.58 kJ/mol.
2. CuCl
2
, FeCl
2
, ZnCl
2
, and AgCl were identified as suitable salts for Na/metal salt or
K/metal salt electrochemical couples based on thermochemical data. Further open circuit
voltage measurements matched those deduced from the thermochemical data.
3. Tubular cells with CuCl
2
as the cathode and Na as the anode were constructed. However,
it was discovered that CuCl
2
was somewhat corrosive and dissolved iron, an element of
the cathode compartment. Since protective coating technology was beyond this Phase I
work scope, no further work on the CuCl
2
cathode was pursued in Phase I.
Notwithstanding, due to its very high OCV and high specific energy, CuCl
2
cathode is a
very attractive possibility for a battery capable of delivering higher specific energy with
higher voltage. Further investigation of the Na-CuCl
2
battery can be done by using
suitable metal coating technologies developed at MSRI for high temperature applications.
4. In Phase I, FeCl
2
and ZnCl
2
were finalized as the potential cathodes for Na-metal salt
batteries for delivering high specific energies. Planar Na-FeCl
2
and Na-ZnCl
2
cells were
designed, constructed, and tested between 350 and 600
o
C. Investigation of
charge/discharge characteristics showed they were the most promising batteries.
Charge/discharge cycles were performed as many as 27 times, and charge/discharge
current was as high as 500 mA. No failure was detected after 50 hours testing.
5. Three-cell planar stacks were designed, constructed, and evaluated. Preliminary tests
showed further investigation was needed for optimization.
6. Freeze-thaw survival was remarkably good for planar BASE discs fabricated by MSRI’s
patented vapor phase process.

3 of 34
TABLE OF CONTENTS
PAGE
EXECUTIVE SUMMARY ……………………………….…………………………………… 2
Technical Objectives of the Proposed Work (Phase I) .….…………………………………… 4
Phase I Work Plan ……………………………………….…………………………………… 4
Phase I Performance Schedule ….……………………….…………………………………… 4
Work Accomplished ……………………………………….…………………………………… 5
Task 1: Identification and acquisition of prospective cathodes for Na- and K-BASE
cathode electrochemical couples through literature search on thermodynamic data …… 5
Task 2: Identification and acquisition of materials for construction of planar cells using
BASE electrolyte plates fabricated in-house …………………………………………10
Task 3: Fabrication of BASE plates and tubes using the MSRI patented vapor phase process ...12
Task 4: Preliminary testing of prospective electrochemical couples using potassium
and sodium anodes, prospective cathodes and BASE tubes .....………………………19
Task 5: Fabrication of cell components for planar cells ……………………………………21
Task 6: Assembly of planar cells with promising cathodes ……………………………………23
Task 7: Electrochemical testing of planar cells ……………………………………………25
Task 8: Post-test evaluation of cells ……………………………………………………………31
Task 9: Final report ……………………………………………………………………………33
Summary/Conclusion …………………………………….……………………………………33
References ……………………………………………………………………………………34

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Technical Objectives of the Proposed Work (Phase I)
Technical objectives of the proposed work for this STTR Phase I, as given in the proposal, are
given in what follows:
1. To fabricate Na-BASE and K-BASE discs and tubes of high ionic conductivity, high
strength, and excellent resistance to moisture attack using a patented, vapor phase
process.
2. To identify suitable cathodes based on thermodynamic data, and other physical properties
(such as weight, melting point, stability, and compatibility with other cell components),
and the measurement of open circuit voltage (OCV) of a number of prospective
electrochemical couples.
3. To design and assemble tubular cells with CuCl
2
as the cathode and Na and K as the
anodes. In Phase II, cells with other cathodes will be investigated.
4. To measure OCV, and investigate charge-discharge characteristics of the cells over a
range of temperatures from 400 to 650
o
C.
5. To design, construct and evaluate performance of planar cells.
Phase I Work Plan:
Task 1: Identification and acquisition of prospective cathodes for K and Na/BASE/cathode
electrochemical couples through literature search on thermodynamic data
Task 2: Identification and acquisition of materials for construction of planar cells using
BASE electrolyte plates fabricated in-house
Task 3: Fabrication of BASE plates and tubes using the MSRI patented vapor phase process
Task 4: Preliminary testing of prospective electrochemical couples using potassium and
sodium anodes, prospective cathodes and BASE tubes
Task 5: Fabrication of cell components for planar cells
Task 6: Assembly of planar cells with promising cathodes
Task 7: Electrochemical testing of planar cells
Task 8: Post-test evaluation of cells
Task 9: Final report
Phase I Performance Schedule:
The proposed schedule of performance for Phase I followed:
Task 1 to be completed by the end of second month from start of project
Task 2 to be completed by the end of second month from start of project
Task 3 to be completed by the end of third month from start of project
Task 4 to be completed by the end of fifth month from start of project
Task 5 to be completed by the end of sixth month from start of project
Task 6 to be completed by the end of seventh month from start of project
Task 7 to be completed by the end of eighth month from start of project
Task 8 to be completed by the middle of ninth month from start of project
Task 9 to be completed by the end of ninth month from start of project

5 of 34
Work Accomplished: Work done during Phase I is described in what follows.
Task 1: Identification and acquisition of prospective cathodes for Na- and K-BASE cathode
electrochemical couples through literature search on thermodynamic data. This task was
successfully completed by the end of second month from the start of the project. The
prospective electrochemical couples identified and acquired are described in the following
paragraphs.
The high temperature rechargeable batteries are comprised of a liquid sodium (or potassium)
anode, a sodium (or potassium) ion-conducting beta” alumina solid electrolyte (Na-BASE) (or
K-BASE), and a liquid metal salt cathode. The correct choice of a metal salt ensures a large free
energy change upon discharge, and thus achieves a high specific energy (Wh/kg). The
prospective electrochemical couples used in the proposed batteries must be sufficiently energetic,
lightweight, must be neither corrosive nor overly volatile, and must be capable of forming a
stable, porous metal structure or a liquid metal in the cathode upon discharge. Since the anode is
liquid sodium (or liquid potassium) at the working temperatures ranging from the proposed 400
to 650
o
C, the possible candidates for the cathode are several metal salts with either low melting
temperature and/or forming eutectics with alkali salts, allowing for a deeper discharge and a
large enough free energy change upon discharge. The maximum amount of electrical energy that
can be derived is
o
GΔ (with 0<Δ
o
G for plausible reactions), where the
o
GΔ is the free
energy of the reaction between sodium (or potassium) and the metal salt to form sodium salt (or
potassium salt) and metal. Such reaction is also called as the displacement reaction. The
corresponding open circuit voltage (OCV) is given by
)/(nFGE
o
Δ=
, where n is the number
of electrons participating the overall displacement reaction and
F
is the Faraday constant
(
F
=96,485 C/mol.).
Wide-ranging literature [1] searches were conducted by looking at materials thermochemical
data and corresponding materials properties. It was discovered that electrochemical couples
formed by metal chloride or metal fluoride possessed high OCV and high specific energy. Table
1 lists a few prospective candidates for the electrochemical couples, which are capable of
delivering more than 200 Wh/kg specific energies for stationary energy storage applications, and
corresponding specific energies calculated at 500
o
C.
Both OCVs and specific energies at 90% efficiency were also calculated for the potential
Na/metal salt and K/metal salt electrochemical couples, identified in Table 1, over the working
temperatures from 350
o
C to 700
o
C. The results are shown in Figure 1 and Figure 2 for OCVs
and specific energies at 90% efficiency, respectively. The calculation results of Na/metal salts
and K/metal salts were plotted in the same figures for comparisons. In both figures, the filled
symbols represent the Na/metal salts couples, and the unfilled symbols represent the K/metal
salts couples. In general, the electrochemical couples comprised of K and metal salts showed
higher OCVs than couples comprised of Na and the corresponding metal salts, except K/AgF.
On the contrary, K/metal salts have lower specific energies than Na/metal salts due to heavy
molecule mass of the electrochemical couples.

Citations
More filters
Journal ArticleDOI
TL;DR: In this article, an electrochemically activated Na/ZnCl2 battery using less-expensive carbon felt to maintain efficient electron percolation in the cathode and evaluates the charge-discharge behavior and cell impedance.

5 citations

Frequently Asked Questions (1)
Q1. What are the contributions in "A high temperature (400 to 650c) secondary storage battery based on liquid sodium and potassium anodes" ?

In this paper, the authors proposed a planar Na-FeCl2 and Na-ZnCl2 batteries to achieve high energy density and high open circuit voltage.