a new cathode material for potassium-ion...

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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Num

ber o

f pap

ers

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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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ü Reversible K storage in K0.6CoO2 is observed in the electrochemical cells.10


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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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

2

3

4

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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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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ü Even after cycling, the crystal structure is not noticeably changed.

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ü The morphology of K0.6CoO2 is not noticeably changed after cycling.

Before cycling After cycling

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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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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


Download these slides at http://ceder.berkeley.edu

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a new cathode material for potassium-ion...

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