Nanoporous NiF2 for energy storage

Yang Yang and James M. Tour

Department of Chemistry, Smalley Institute for Nanoscale

Science and Technology, Rice University

http://www.jmtour.com/

yymater@gmail.com and tour@rice.edu

Device fabrication process

(i) plasma treatment (ii) sputter Cr/Au (iii) electrodeposit metal layer

(iv) anodizationto form porous layer

(v) preparation of solid electrolyte

(vi) supercapacitor device assembly

(vii) ready for testing

b c

a

200 nm

~ 900 nm

a

200 nm

b

200 nm

c d

d110 = 0.32 nm

-0.8 -0.4 0.0 0.4 0.8

-20

-10

0

10

20 10 V s-1

20 V s-1

50 V s-1

100 V s-1

Potential (V)

Curr

ent (

mA)

a

0 5 10 15 20 25

-0.8

-0.4

0.0

0.4

0.8

Time (s)

Pote

ntia

l (V)

b

-1.5 -1.0 -0.5 0.0 0.5 1.0 1.5-20

-10

0

10

20 10 mV s-1

20 mV s-1

Potential (V)

Curr

ent (m

A)

c

0 200 400 600 800-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

Time (s)

Pote

ntia

l (V)

d

Double layer capacitor: 0.29 mF cm-2 (3.2 F cm-3 or 1.57 F g-1), energy density of 0.6 Wh kg-1 and power density of 8 kW kg-1 Pseudocapacitor: 66 mF cm-2 (733 F cm-3 or 358 F g-1), energy density of 384 Wh kg-1 and power density of 112 kW kg-1

Ni(OH)2 + OH- NiOOH + H2O + e-

NiF2 + 2OH- Ni(OH)2 + 2F-

Proposed charge storage mechanism :

Advantages of nanoporous NiF2

1. Wide operation potential window – high energy density

2. Long term stability – reliable performance

3. Li-free, battery-like supercapacitors – works easily

4. Can be used for Ni-Cd and Ni-MH batteries

5. Easy fabrication – only needs a power source

6. Can be grown on any substrates, any shapes, any sizes