a new cathode material for potassium-ion...
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A New Cathode Material for Potassium-Ion Batteries
Haegyeom Kim, Jae Chul Kim, Shou-Hang Bo, Tan Shi, Deok-Hwang Kwon, and Gerbrand Ceder*
Post-doc Fellow in Ceder groupMaterials Sciences DivisionLawrence Berkeley National Laboratory
Abstract #: A02-0154 Monday, 29 May 2017 13:40-14:00
H. Kim et al. Adv. Energy Mater. 1700098 (2017) Download these slides at http://ceder.berkeley.edu1
L. Gaines et al. Report#ANL/ESD-42. Argonne National Laboratory May (2000)
Low cost
High power
High stability
Toward Large Scale Applications
High energy
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• Global market for Li-ion batteries
increases 22%/year.
• 35% of all lithium are already used by
Li-ion industry.
• Li resources are geographically
localized: rapid variations in price with
demand.
"An Increasingly Precious Metal." The Economist. The Economist Newspaper, 14 Jan. 2016.
ü Li-ion battery technology cannot meet the increasing demands on large scale energy storage systems, including electric vehicles and grids.
https://minerals.usgs.gov/minerals/pubs/commodity/lithium/mcs-2016-lithi.pdf
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Concentrationinseawater (mg/L)
Cl- 18,980Na+ 10,556
SO42- 2,649Mg2+ 1,262Ca2+ 400K+ 380Li+ 0.1
Li2CO3 Na2CO3 K2CO3
$7,000/ton $240/ton $450/tonCu Al Al$5,000/ton $1,500/ton $1,500/ton
www.alibaba.com, accessed March 2017
http://periodictable.com/Properties/A/CrustAbundance.html Accessed May 2017.
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Standard potentials(vs. SHE)
Li/Li+ Na/Na+ K/K+
Aqueous -3.04 -2.714 -2.936PC solvent -2.79 -2.56 -2.88
EC/DEC solvent(relative value)
0.0 0.3 -0.15
Komaba et al. Electrochem. Commun. 2015, 60, 172,
ü Lower standard redox potential of alkali ions
è Potentially higher working voltage of battery system
Working voltage
Standard redox potential of A/A+
Standard redox potential of A/A+
Redox potential of electrode
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Komaba et al. Electrochem. Commun. 2015, 60, 172,
ü Graphite can store and release K ions, but not Na.
ü It indicates we already have a good anode material!!!
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ü Recently, K-ion batteries attract much attention.H. Kim et al.In preparation. 7
2000 2002 2004 2006 2008 2010 2012 2014 2016 20180
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Search at March 1st, 2017
ü Transition metal component
èHigh redox activity
ü 2-dimensional K migration pathways
èGood rate capability
ü Rigid oxide framework
è Good cycle stability
Xiang et al. J. Electrochem. Soc. 2015, 162, A1662
Layered transition metal oxides (KxTMO2, TM= Transition Metal) can be
promising cathode candidates for K-ion batteries.
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H. Kim et al. Adv. Energy Mater. 1700098 (2017)
ü P2-type K0.6CoO2 was synthesized by a conventional solid-state method.
ü The smaller K content (compared to Na) likely results from the largerionic size of K.
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H. Kim et al. Adv. Energy Mater. 1700098 (2017)
ü Reversible K storage in K0.6CoO2 is observed in the electrochemical cells.10
H. Kim et al. Adv. Energy Mater. 1700098 (2017)
ü Reversible K release/storage in K0.6CoO2 is observed in the electrochemical cells.
Two theta (Deg. Mo)Voltage (V vs. K)
Tim
e (H
ours
)
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H. Kim et al. Adv. Energy Mater. 1700098 (2017)
ü Upon charge, (008) peak moves to lower angle, indicating the increase ofCoO2 slab distance.
ü (008) peak moves back to the original position, indicating reversiblereactions.
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J. Electrochem. Soc. 1994, 141, 2972
Slope of voltage curves increases
Nat. Mater. 2011, 10, 74
O3-LiCoO2 P2-Na0.74CoO2 P2-K0.6CoO2
1 V per 0.6 Li transfer 2.3 V per 0.35 K transfer1.8 V per 0.52 Na transfer
(1.66 V/Li+) (6.57 V/K+)(3.46 V/Na+)
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Li+ (0.76 Å) Na+ (1.02 Å) K+(1.38 Å)Ionic size of alkali ions
Slab distance for alkali ions in
LiCoO2 (2.64 Å) Na0.74CoO2 (3.43 Å) K0.6CoO2(4.25 Å)
ü Less screening of electrostatics between K ions by oxygen results in
much larger effective interaction, forming remarkable amount of phase
transitions.
J. Electrochem. Soc. 1994, 141, 2972 Nat. Mater. 2011, 10, 74
O3-LiCoO2 P2-Na0.74CoO2 P2-K0.6CoO2
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H. Kim et al. Adv. Energy Mater. 1700098 (2017); Clement et al. J. Electrochem. Soc. 2015, 162, A2589, Mo et al. Chem. Mater. 2014, 26, 5208
ü P2-K0.6CoO2 can provide a reversible capacity of ~43 mAh/g at 150 mA/g
0 20 40 60 80 1001
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3
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Volta
ge (V
vs.
K)
Capacity (mAh g-1)
150, 120, 100, 70, 10, 2 mA g-1
0 2 4 6 8 100
20
40
60
80
100
2 mA g-1
10 mA g-1
70 mA g-1
100 mA g-1
120 mA g-1
150 mA g-1
Cap
acity
(mA
h g-1
)Number of cycles
ü Good rate capability would be attributable to P2 structure.
O-type structure P-type structure
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H. Kim et al. Adv. Energy Mater. 1700098 (2017)
ü P2-K0.6CoO2 cathode can maintain ~60% of the initial capacity after 120 cycles
ü After refreshing the cells, the capacity was recovered.
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H. Kim et al. Adv. Energy Mater. 1700098 (2017)
ü Even after cycling, the crystal structure is not noticeably changed.
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H. Kim et al. Adv. Energy Mater. 1700098 (2017)
ü The morphology of K0.6CoO2 is not noticeably changed after cycling.
Before cycling After cycling
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H. Kim et al. Adv. Energy Mater. 1700098 (2017)
ü The surface of K0.6CoO2 becomes amorphous-like and nano-sized
particles, which will be responsible for some capacity decays.
Before cycling After cycling
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H. Kim et al. Adv. Energy Mater. 1700098 (2017)
ü A full cell consisting of K0.6CoO2 cathode and graphite anode workssuccessfully.
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üNew P2-type K0.6CoO2 cathode is proposed for KIBs.
üP2-type K0.6CoO2 shows reversible K storage properties.
üMultitude phase transitions occurs in KxCoO2 during K
de/intercalation, while it maintains P2-type structure.
üSurface degradation affects capacity decay of K0.6CoO2.
üPractical feasibility of KIB is demonstrated while further
optimization is required.
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Gerbrand Ceder,
Chancellor’s Professor
Department of Materials Science and Engineering
Dr. Jae Chul Kim Prof. Shou-Hang Bo Mr. Tan Shi Dr. Deok-Hwang KwonThe Laboratory Directed Research and Development Program of
Lawrence Berkeley National Laboratory under U. S. Department of
Energy (DE-AC02-05CH11231)22
Thank you
H. Kim et al. Adv. Energy Mater. 1700098 (2017)
Download these slides at http://ceder.berkeley.edu
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