[PPT] - New Electrode Materials and Electrolyte Solutions for Solutions for PowerPoint Presentation

SLIDE 1

New Electrode Materials and Electrolyte Solutions for Rechargeable Li ion batteries

Doron Aurbach Elena Markevich Valentina Baranchugov Elad Pollak Gregory Salitra Ella Zinigrad Boris Markovsky Liraz Larosh Yossi Talyossef Maxim Koltypin

Solutions for Rechargeable Li ion Batteries.

Department of Chemistry, Bar-Ilan University, Ramat-Gan 52900, Israel

SLIDE 2

A scheme of a typical secondary battery Li-ion battery based on LixC6/LixCoO2 electrochemistry LiPF6 solutions in alkyl carbonates mixtures

SLIDE 3

R&D of high voltage cathodes
R&D of new electrolyte solutions (better safety)
Pushing the capacity to high values
Nano materials/nano composites.
Maintaining a very high level of science:

precise measurements using the most sophisticated techniques (SS NMR, Raman, FTIR, HR Microscopy, SPM, XRD, Neutron D, Sincherotron radiation for XANES, EXAFS, fine XRD, all the fine electrochemical techniques – SSCV, PITT, GITT, EIS, EQCM, in situ measurements) and high level ab initio calculations. Advances in rechargeable Li battery technology:

SLIDE 4

Pros

High surface area – low
verall charge transfer

resistance

Small size – small

diffusion length. Li intercalation processes may be controlled by SS diffusion of Li ions in the host. Small diffusion length – faster insertion

High surface area – high
reactivity. None of the

cathode/anode materials in Li batteries are intrinsically stable with the electrolyte solutions.

Small size – problems
f electrical contact and

electrical integrity of the active mass.

Cons Example: Nano vs. micro LiMn1.5Ni0.5O4 spinel and LiMn0.5Ni0.5O2 layered cathode materials.

SLIDE 5

1.2
0.9
0.6
0.3

0.3 0.6 0.5 1 1.5 2 2.5 3

V I ( mA

LiBOB ec:pc 2:3 LiPF6 ec:pc 2:3

I (mA) Voltage (V vs Li/Li+) Note the huge irreversible capacity in LiPF6 solutions Much better CV resolution and small irreversible capacity with LiBOB solutions.

b a

1.2
0.9
0.6
0.3

0.3 0.6 0.5 1 1.5 2 2.5 3

V I ( mA

LiBOB ec:pc 2:3 LiPF6 ec:pc 2:3

I (mA) Voltage (V vs Li/Li+) Note the huge irreversible capacity in LiPF6 solutions Much better CV resolution and small irreversible capacity with LiBOB solutions.

1.2
0.9
0.6
0.3

0.3 0.6 0.5 1 1.5 2 2.5 3

V I ( mA

LiBOB ec:pc 2:3 LiPF6 ec:pc 2:3

I (mA)

1.2
0.9
0.6
0.3

0.3 0.6 0.5 1 1.5 2 2.5 3

V I ( mA

LiBOB ec:pc 2:3 LiPF6 ec:pc 2:3

1.2
0.9
0.6
0.3

0.3 0.6 0.5 1 1.5 2 2.5 3

V I ( mA

LiBOB ec:pc 2:3 LiPF6 ec:pc 2:3

I (mA) Voltage (V vs Li/Li+) Note the huge irreversible capacity in LiPF6 solutions Much better CV resolution and small irreversible capacity with LiBOB solutions.

b a

1M 1M LiBOB LiBOB/EC:PC 2:3 /EC:PC 2:3 1M LiPF 1M LiPF6

6/EC:PC 2:3

/EC:PC 2:3

1.2
0.9
0.6
0.3

0.3 0.6 0.5 1 1.5 2 2.5 3

V I ( mA

LiBOB ec:pc 2:3 LiPF6 ec:pc 2:3

I (mA) Voltage (V vs Li/Li+) Note the huge irreversible capacity in LiPF6 solutions Much better CV resolution and small irreversible capacity with LiBOB solutions.

b a

1.2
0.9
0.6
0.3

0.3 0.6 0.5 1 1.5 2 2.5 3

V I ( mA

LiBOB ec:pc 2:3 LiPF6 ec:pc 2:3

I (mA) Voltage (V vs Li/Li+) Note the huge irreversible capacity in LiPF6 solutions Much better CV resolution and small irreversible capacity with LiBOB solutions.

1.2
0.9
0.6
0.3

0.3 0.6 0.5 1 1.5 2 2.5 3

V I ( mA

LiBOB ec:pc 2:3 LiPF6 ec:pc 2:3

I (mA)

1.2
0.9
0.6
0.3

0.3 0.6 0.5 1 1.5 2 2.5 3

V I ( mA

LiBOB ec:pc 2:3 LiPF6 ec:pc 2:3

1.2
0.9
0.6
0.3

0.3 0.6 0.5 1 1.5 2 2.5 3

V I ( mA

LiBOB ec:pc 2:3 LiPF6 ec:pc 2:3

I (mA) Voltage (V vs Li/Li+) Note the huge irreversible capacity in LiPF6 solutions Much better CV resolution and small irreversible capacity with LiBOB solutions.

b a

1M 1M LiBOB LiBOB/EC:PC 2:3 /EC:PC 2:3 1M LiPF 1M LiPF6

6/EC:PC 2:3

/EC:PC 2:3

The voltammetric behavoir of Li intercalation into MCMB graphite in 2

solutions. a- LiPF6 EC:PC 2:3

b- LiBOB EC:PC 2:3

MCMB electrodes

SLIDE 6

0.5 1 1.5 2 2.5 250 500 750 1000 1250 1500 1750 2000 2250 2500 Capacity, mAh/g Voltage, V

1M LiClO4 1M LiBOB

1M LiBOB/EC:PC 2:3 1M LiClO4/EC:PC 2:3

0.5 1 1.5 2 2.5 250 500 750 1000 1250 1500 1750 2000 2250 2500 Capacity, mAh/g Voltage, V

1M LiClO4 1M LiBOB

1M LiBOB/EC:PC 2:3 1M LiClO4/EC:PC 2:3

The first and consecutive galvanostatic cycles of KS25 graphite electrode in LiBOB and LiClO4 solutions.

Synthetic graghite flakes

SLIDE 7

40 90 140 190 240 290 340

DSC curves of 1M LiPF6 solutions in EC:DMC 1:1 and PC in the presence of Li metal at heating rate of 1°C min-1 DSC curves of 1M LiBOB solutions in EC:DMC 1:1 and PC in the presence of Li metal at heating rate of 1°C min-1

40 90 140 190 240 290 340

PC EC:DMC 0.5 W g-1 Temperature, °C 2 W g-1 Temperature, °C PC EC:DMC

exo exo LiPF6 solutions + Li metal LiBOB solutions + Li metal Aurbach & Al, J. Power Sources, (2007) in press

SLIDE 8

Liquidity over a wide temperature range Non-volatility Non-flammability High thermal stability High ionic conductivity ( over 10-2 S cm-1 at r.t.) Wide electrochemical window: the high anodic stability enables the use of a large variety of cathode materials in ionic liquid electrolytes, including materials which red-ox activity is around 5V vs. Li/Li+ Remarkable dissolution properties for organic as well as inorganic substrates, including Li and Mg salts. ▪ ILs are expected to be inert towards magnesium

Properties of Ionic Liquids, which make them promising electrolyte solution components for Li-ion and magnesium batteries Properties of Ionic Liquids, which make them promising electrolyte solution components for Li-ion and magnesium batteries

IL systems ensure very good safety features

SLIDE 9

1.5
1.0
0.5

0.0 0.5 1.0 1.5 2.0 2.5 3.0 1 2 3 4 5 6 E, V I, mA

0.8
0.6
0.4
0.2

0.0 0.2 0.4 0.6 0.8 1.0 1 2 3 4 5 6 7 E, V I, mA

0.8
0.6
0.4
0.2

0.0 0.2 0.4 0.6 0.8 1.0 1 2 3 4 5 6 E, V I, mA

Electrochemical windows of the imidazolium-based ionic liquids Electrochemical windows of the imidazolium-based ionic liquids Working electrode: glassy carbon (0.2 cm2), R.E.: Li/Li+, scan rate 20 mV/s, 250C.

The cathodic limit of imidazolium derivatives is relatively high (about 1V vs. Li/Li+). However, they can be used in Li batteries using passivation agents in solutions.

Do not dissolve Li salts Dissolves Li salts

SLIDE 10

One of the main advantages of room temperature ionic liquids – their high anodic stability - may be well exploited for the use of 5V LiNi0.5Mn1.5O4 spinel cathodes.

1.5
1.0
0.5

0.0 0.5 1.0 1.5 2.0 1 2 3 4 5 6 E, V I, mA

N C4H9 CH3 BF4 LiCoO2 LiNi0.5Mn1.5O4

1.5
1.0
0.5

0.0 0.5 1.0 1.5 2.0 1 2 3 4 5 6 E, V I, mA

N C4H9 CH3 BF4 LiCoO2 LiNi0.5Mn1.5O4

Electrochemical window of BMIBF4 measured on glassy carbon electrode and insertion-deinsertion potential regions of LiCoO2 and LiNi0.5Mn1.5O4 cathode materials

50 100 150 200 250 20 40 60 80

Cycle number Capacity, mA h/g

C/6 C/2

N C2H5 CH3 BF4

1 2 3 4 2 4 6 8 10 Time, hours E, V

300C 30 5-20 1 1 30 5-20 1

1 2 3 4 2 4 6 8 10 Time, hours E, V

300C 30 5-20 1 1 30 5-20 1

300C

50 100 150 200 250 20 40 60 80

Cycle number Capacity, mA h/g

C/6 C/2

N C2H5 CH3 BF4

1 2 3 4 2 4 6 8 10 Time, hours E, V

300C 30 5-20 1 1 30 5-20 1

1 2 3 4 2 4 6 8 10 Time, hours E, V

300C 30 5-20 1 1 30 5-20 1

50 100 150 200 250 20 40 60 80

Cycle number Capacity, mA h/g

C/6 C/2

N C2H5 CH3 BF4

1 2 3 4 2 4 6 8 10 Time, hours E, V

300C 30 5-20 1 1 30 5-20 1

1 2 3 4 2 4 6 8 10 Time, hours E, V

300C 30 5-20 1 1 30 5-20 1

300C

Aurbach, Markevich, Baranchugov , Electrochem. Comm.(2006)

SLIDE 11

Why silicon? 1. Very high capacity (> 4000 mAh/gr , better than that of Li metal). 2. Much better safety features, compared to Li metal. 3. Problems

f

co-intercalation

f

solvent molecules into carbonaceous materials do not exist with silicon.

SLIDE 12

Electrochemical window of the neat ionic liquid 1-methyl-1-propylpiperidinium bis(trifluoromethylsuphonil)imide, W.E. glassy carbon A passivation process takes place during the cathodic polarization of MPPpTFSI solutions, even in the absence of Li salt . This passivation process enables the use of the additive free MPPpTFSI ionic liquid together with a Li salt, as an electrolyte solution for Li batteries. The cathodic peak, seen in the first CV cycle of the neat IL relates to the reduction of the anion.

0.8
0.6
0.4
0.2

0.2 0.4 0.6 0.8

1

1 2 3 4 5 6 7

E, V I, mA

20mVs-1, 250C

The 1st anodic polarization on freshly polished W.E. The 1st canodic polarization on freshly polished W.E. The 2nd canodic polarization N C3H7 N(SO2CF3)

2

SLIDE 13

CV of a thin film silicon electrode and of the stainless steel disc substrate (blank) in 1M LiTFSI / MPPpTFSI in 3 electrode coin-cell The shape of the initial charging CV curve differs from the second one. Possible reasons are: Reduction of some some solution components Irreversible consumption of Li by dangling bonds Existence of a nucleation barrier in the first Li-Si phase formation reaction of Li ions with surface SiOx, with Li2O formation

0.3
0.2
0.1

0.1 0.2

0.5

0.5 1 1.5

E,V I, mA

1st cycle 2nd cycle blank 0.1mVs-1 The selective Li-Si binary alloy formation

n

the thin Si film, sputtered

n

identical stainless steal disk, could be measured in these systems down 0V

vs. Li/Li+, with no

interference from the SS current collector and the solution.

Initial irreversible capacity 17%

Aurbach, Markevich, Baranchugov,Salitra, Polak,

Electrochem. Comm.

(2007)in press.

SLIDE 14

Galvanostatic cycling of a Si/ Li cell and a LiCoO2/Si (Si limited) cell (60% excess of LiCoO2 relative to Si ) 1000 2000 3000 4000 5000 6000 10 20 30 40

Cycle number Capacity, mAhg-1

1 2 3 10 20 30 40 Time, h E, V

Si/Li LiCoO2/Si

1 2

1000 2000 3000 4000 5000 6000 10 20 30 40

Cycle number Capacity, mAhg-1

1 2 3 10 20 30 40 Time, h E, V

Si/Li LiCoO2/Si

1 2

(C/16) (C/10 with respect to Si electrode)

The challenge is to operate 5 V batteries Si-LiMn1.5Ni0.5O4 (experiments underway) First testing

SLIDE 15

3.5 V 2 V 3.75 V 4.05 V 3 V 130 mAh/gr

1-st cycle 2-nd cycle

200 µV/sec



4.4 3.4 2.4 1.4 E, Volts 0.7 0.2

0.3
0.8

Z ”

150
100
50

00 50 100 150



Z’ I, mAmps.cm-2

Typical CV and Impedance spectra of composite LiFePO4 olivine cathode (theoretical capacity: 170 mAh/gr) cycled in standard LiClO4 1M in EC/DMC solution

Aurbach, Koltypin, Nazar, Ellis, Electrochem.Solid.State.Letters (2007) In press

SLIDE 16

LiClO4 1M EC/DMC, LiPF6 1M EC/DMC LiPF6 1M EC/DMC + 100 ppm H2O LiClO4 1M EC/DMC 60 oC LiPF6 1M EC/DMC Li2CO3, 60 oC LiPF6 1M EC/DMC, 60 oC, LiPF6 1M EC/DMC + 100 ppm H2O, 60 oC

% of atomic iron dissolved

10 20 30 40 50 60

60 oC 30 oC LiPF6 1M EC/DMC + Silazide 60 oC LiPF6 1M EC/DMC +silazane, 60oC

Dissolution of iron from LiFePO4 olivine compounds stored in different solution with and without additives.

SLIDE 17

Stable behavior 30 oC 30 oC Fresh electrode After 10 days

f storage

60 oC

c d b

3.5 V, 15 days storage 4.05 V 3.5 V

60 oC

a

LiPF6 1M EC/DMC Initial capacity ~160 mAh/gr Final capacity ~160 mAh/gr 30 oC capacity ~130 mAh/gr 60 oC capacity ~160 mAh/gr LiPF6 1M EC/DMC LiClO4 1M EC/DMC

25 50 75 100

100
75
50
25

Z' Z''

4_05V_Un1Ch7.z 4_05V 10 days_Un1Ch7.z 3_5V10 days_Un1Ch7.z 3_5V_Un1Ch7.z

LiPF6 1M EC/DMC

30 oC

4.05 V, 15 days of storage 4.05 V 3.5 V

3.5 V, 10 days of storage

b

Fresh electrode After 15 days

f storage

10 20 30 40 50

50
40
30
20
10

Z' Z''

3 V H batch #4 LiPF6 15 days 60 oC Wide_Un1Ch6.z 4 V H batch #4 LiPF6 15 days 60 oC Wide_Un1Ch6.z 3 V H #4 LiClO4 60 oC_Un1Ch5.z 4_05V H #4 LiClO4 60 oC_Un1Ch5.z

LiClO4 1M EC/DMC 4.05 V 4.05 V, 15 days of storage 3.5 V, 15 days

f storage

3.5 V

60 oC

1-st cycle 2-nd cycle 60 oC Initial capacity ~160 mAh/gr Final capacity ~145 mAh/gr 4.05 V, 15 days

f storage

     LiPF6 1M EC/DMC

100
50

50 100

Z ” Z’

500



250

Z ”

250 500

Z’

50
25

25 50

Z ”

After 15 days of storage 12 2

8
18

1.5 2.5 3.5 4.5 E, Volts 1.5 2.5 3.5 4.5 E, Volts I, mAmps.cm-2 2

2

3.5

1.5
6.5

1.5 2.5 3.5 4.5 E, Volts

Z’

I, mAmps.cm-2 I, mAmps.cm-2 I, mAmps.cm-2

Fresh, fist 3 cycles

Fresh electrode first 3 cycles 1st cycle 2nd cycle 2nd cycle 3rd cycle first 2 cycles

SLIDE 18

50 100 150

150
100
50

Z' Z''

3 V b #1 PF6 100pmm 15 days 60 oC_Un1Ch6.z 4_05V b #1 PF6 100pmm 15 day s 60 oC_Un1Ch6.z 3 V B # 1 PF6 100 ppm 15 day s 60 oC_Un1Ch6.z 4_05V B # 1 PF6 100 ppm 15 days 60 oC_Un1Ch6.z

10 20 30 40 50

50
40
30
20
10

Z' Z''

3 V b #4 LiClO4 60 oC_Un1Ch6.z 4_05V b #4 LiClO4 60 oC_Un1Ch6.z 3 V B # 4 LiCO4 15 days 60 oC_Un1Ch6.z 4_05V B # 4 LiCO4 15 days 60 oC_Un1Ch6.z

a

Fresh electrode After 15 days of storage After 15 days

f storage

60 oC

Initial cycle Fresh electrode

c

After 15 days

f storage

4.05 V fresh 3 V, 20 days

f storage

3 V fresh 4.05 V, 20 days of storage

60 oC

4.05 V fresh 4.05 V, 20 days of storage 3 V fresh 3 V, 20 days of storage

Sol-gel Synthesis

LiClO4 in EC/DMC LiPF6 in EC/DMC + 100 ppm H2O

5 1

9

I, mAmp.cm-2 11 1

9
19

I, mAmp.cm-2 1.5 2.5 3.5 4.5 1.5 2.5 3.5 4.5 E, volts E, volts

50
40
30
20
10

50 40 30 20 10

Z ”

150
100
50

Z ”

150 100 50

Z’  Z’ 

Capacity: 157 mAh/gr Capacity: 117 mAh/gr

60 oC

Aurbach, Koltypin, Nazar, Ellis,

J. Power Sources

(2006) and (2007) In press

SLIDE 19

Intensity (CPS) 35 30 25 20 15 10 692 690 688 686 684 682

Binding energy, eV

Intensity (CPS) 240 200 150 120 80 40 292 290 288 286 284 282

Binding energy, eV

F(1s) C(1s) O(1s) P(1s)

100 80 60 40 Intensity (CPS) 198 196 194 192 190 188 186

Binding energy, eV

100 80 60 40 20 538 536 534 532 530 528 Intensity (CPS)

Binding energy, eV

pristine pristine aged aged pristine pristine pristine aged aged aged pristine pristine pristine aged aged aged aged pristine

XPS spectra of pristine and aged LiFePO4 olivine electrodes (without additives).

SLIDE 20

Carbon coating Crystalline material

Core-Shell, carbon coated , nano V2O5

Swagelock reactor.

VO(OR)3  CCV2O3 (400 0C,Air) CCV2O5 Aurbach, Odeni, Pol, Koltypin and Gedanken, Adv. Mater.(2006)

SLIDE 21

Carbon coating Crystalline material

SLIDE 22

CCV2O5 + 0.2 % intrinsic carbon (10 % CB)

Cyclic voltammetry of composite cathode comprised nanometric carbon coated V2O5 at 2- 4 V and 3- 4 V range

100 µV /sec 2-4 V 3-4 V 100 µV /sec

0.35

0.35

2.75 3 3.25 3.50 3.75 4

I(mA·cm-2)

0.35

0.35

1.5 2 3 2.5 3.5 4

I(mA·cm-2) E, volts vs. Li/Li+ E, volts vs. Li/Li+ Koltypin,Pol,Gedanken & Aurbach, J. Electrochem.Soc.(2007) In press.

SLIDE 23

Lithiation capacities of nanometric carbon coated V2O5 composite cathode and cathode comprised with micronic V2O5 particles cycled vs. Li/Li+ Nanoparticles Nanoparticles

SLIDE 24

2-4 V potential range

SLIDE 25

Up to 5C fast cycling

More than 100 mAh/gr at 5C scan rate for carbon coated nano V2O5 !!!

SLIDE 26

3.25 V (2-4 V range) 3.25 V (3-4 V range) 3.25 V (3-4 V range) 4 V (3-4 V range) 4 V (2-4 V range) 3.25 V (3-4 V range) 4 V (2-4 V range) 4 V (3-4 V range) 3.25 V (3-4 V range) 3.25 V (2-4 V range) 4 V (3-4 V range) 4 V (2-

4 V range)

0.2 % C

2.4 % C

500 1000 1500 2000 500 1000 1500 2000 Z’  Z’’  Z’’  250 500 750 250 500 750 100 200 300 100 200 300 Z’  Z’’  Z’ 

Micronic No carbon

7. Comparison of impedance spectra of

embedded vanadium oxide, taken at 60

C at randomly chosen potentials for

wide and narrow potential range of cycling as indicated; (a) impedance of embedded CCVO (0.2 % C) electrode, (b) impedance of embedded CCVO (2.4 % C) electrode and (c) impedance of micronic V2O5 embedded cathode, all in LiClO4 1M in EC/DMC .

SLIDE 27

Substituted LiMn2O4-spinel materials LiMxMn2-xO4. Manganese is partially replaced by other transition metals: M=Ni, Co, Cu, Cr, Zn, Fe

Li Mn

Li (8a) Mn/Ni (16d) O (32e)

Y. Ein-Eli, W.F. Howard, Jr., S.H. Lu et al. J. Electrochem. Soc.,

145, 1238 (1998);

Y. Shin, A. Manthiram, Electrochim. Acta, 48, 3583 (2003)

Substituted LiMnO2- layered compounds LiMxMn1-xO2. Manganese is partially replaced by other transition metals: M=Ni, Co, Cu.

M. Spahr et al J. Electrochem. Soc., 145, 1113 (1998);
Y. Makimura, T. Ohzuku, J. Power Sources, 119-121, 156 (2003)

Cathodes for High-Energy Density 5-Volt Lithium-ion Batteries

SLIDE 28

Nano-sized LiNi0.5Mn1.504 vs. Micro-sized LiNi0.5Mn1.504

100 200 300

2-Theta - Scale

11 20 30 40 50 60 70

111 311 400 222 331 333 440 531

W=0.17 W=0.32 W=0.18 W=0.46 W=0.25 W=0.48

Micro-sized particles Nano-sized particles Intensity/ counts.s-1

Raman shift/ cm-1

100 200 300 400 500 600 700 800 900

407 500

640

Micro-sized particles Nano-sized particles

50 50

592

Intensity/ a.u.

496 596 638 400 w=28 w=19 w=13 w=75

w=31

w=32

530

527

Clusters of nanoparticles Oriented micro- particles =300 Vs-1, T=300C

E/ V

4.3 4.4 4.5 4.6 4.7 4.8 4.9

I/ A.g

1
2e-6
1e-6

1e-6 2e-6 Micro-particles Nano-particles Ni3+ Ni4+ Ni2+ Ni3+ Ni3+ Ni4+ Ni2+ Ni3+

SLIDE 29

Micro-particles

Rate of discharge

C/10 C/8 C/6 C/4 C/2 1C

Discharge capacity / mAh.g

1

60 80 100 120 140 1-st 2-nd 3-rd

Nano-particles

Rate of discharge

C/10 C/8 C/6 C/4 C/2 1C

Discharge capacity / mAh.g

1

60 80 100 120 140 1-st 2-nd 3-rd

Consequtive tests Consequtive tests

Capacity retention 59% Capacity retention 84%

Spinel LiNi0.5Mn1.5O4 EC-DMC (1:2)/1.5 M LiPF6

Talyossef, Markovski,Kovacheva , Aurbach, Electrochem. Comm. (2005) Talyossef, Markovski,Kovacheva ,Aurbach, Electrochem. & SS.Lett. (2006) Talyossef, Markovski,Kovacheva ,Aurbach, J. Electrochem. Soc. (2007) In press.

SLIDE 30

E / V vs. Li/Li

+

4.3 4.4 4.5 4.6 4.7 4.8 4.9 I / A.cm-2

2e-6
1e-6

1e-6 2e-6

Pristine particles Particles aged in solution (700C)

Scan rate 10 V/s 4.71 V 4.76 V 4.72 V 4.69 V

No remarkable changes in reversibility, kinetics and capacity fading of electrodes comprising aged LiNi0.5Mn1.5O4 particles

Micro-sized LiNi0.5Mn1.5O4, DMC-EC (2:1)/1.5M LiPF6

SLIDE 31

2D Graph 7

Raman shift / cm-1

100 200 300 400 500 600 700 800 900

407 500 640

Pristine micro-sized particles Pristine nano-sized particles 50 50

592

Intensity / a.u.

496 596 638 400-407 w=28 w=19 w=13 w=75 w=31 w=32 530 527 662

Intensity / a.u. Raman shift / cm-1

100 200 300 400 500 600 700 800 900

Micro-sized particles aged in solutions, 700C

100

407 499 639 596 660

w=36 w=20 w=12

530

Intensity / a.u.

407

w=85

498

w=28

537 638 665

w=23

50 Intensity / a.u.

Nano-sized particles aged in solutions, 700C

Micro- and Nano-LiNi0.5Mn1.5O4: ageing in DMC-EC/LiPF6 solutions at 700C

SLIDE 32

3000
2000
1000

1000 2000 3000 2 4 6 8 10 12 14

Z'' / Ohm Z' / Ohm Time of ageing / days

3.97 Hz 31.6 mHz 12.6 mHz 7.92 Hz 15.8 mHz

a

400
300
200
100

100 200 300 400 2 4 6 8 10 12 14

Z'' / Ohm Z' / Ohm Time of ageing / days

15.8 Hz 5 mHz 5 mHz 12.6 Hz 20 Hz

b

Micro-particles Nano-particles

E=4.75 V

Spinel LiNi0.5Mn1.5O4 60 0C

Talyossef, Markovski, Kovacheva & Aurbach, J. Power Sources (2006)

SLIDE 33

E / V vs. Li/Li+

2.0 2.5 3.0 3.5 4.0 4.5 5.0

I / A.cm-2

8e-5
4e-5

4e-5 8e-5

1st and 2nd CVs Ecut-off = 4.50 V Ecut-off = 4.55 V Ecut-off = 4.65 V

3.85 V 3.56 V 3.00 V 2.76 V OCV 1st 2nd

Ni2+/Ni3+/Ni4+ T=600C =50 V/s

Nano

=50 V/s T=600C

E / V vs. Li/Li+

2.5 3.0 3.5 4.0 4.5

I / A.g-1

.06
.04
.02

0.00 .02 .04 .06 .08

1st 2nd 3rd

Micro

Layered LiNi0.5Mn0.5O2 DMC-EC (2:1)/1.5M LiPF6

SLIDE 34

T=600C

Rate of discharge

C/10 C/5 C/2.5 1C

Discharge capacity / mAh.g-1

50 100 150 200

Nano-particles Micro-particles

T=300C

Rate of discharge

C/10 C/5 C/2.5 1C

Discharge capacity / mAh.g-1

50 100 150 200

Nano-particles Micro-particles

53% 26% 53% 12%

Layered LiNi0.5Mn0.5O2 EC-DMC (1:2)/1.5 M LiPF6

SLIDE 35

Cycle number

5 10 15 20

Discharge capacity / mAh.g-1

60 80 100 120 140 160 180 200

T=300C T=600C

Ecut-off / V

4.1 4.2 4.3 4.4 4.5 4.6

Discharge capacity / mAh.g-1

160 170 180 190

Stable electrochemical behavior in cycling by CC – CV mode (2.5 V – 4.5 V range)

r2=0.998

Layered Nano-LiNi0.5Mn0.5O2 EC-DMC (1:2)/1.5 M LiPF6

SLIDE 36

Z' / Ohm

1000 2000 3000 4000

1000

1000 2000 3000 4000

1000

1000 2000 3000 4000

1000

1000 2000 3000 4000

Z'' / Ohm

1000

a b c d

Nano-LiNi0.5Mn0.5O2 T=600C, E=3.90 V

20 mHz 1 Hz 20 mHz 31.5 Hz 5 Hz 250 mHz 10 Hz 200 mHz Rsf=167 Ohm Rsf=144 Ohm Rsf=157 Ohm Rsf=151 Ohm

Initial steady-state by electrode’s cycling at 600C 1 week ageing, 600C 2 weeks ageing, 600C 50 days cycling and ageing, 600C

After the impedance of nano-LiNi0.5Mn0.5O2 electrodes reaches its steady values, it remains almost stable during prolonged ageing and cycling at elevated temperatures

SLIDE 37

Nano-LiNi0.5Mn0.5O2 EC-DMC (1:2)/1.5 M LiPF6

Pristine Aged at 600C EC Absorbance Wavenumbers (cm-1) Li2CO3 Li2CO3 Ni – O Mn – O LixPFy Poly- carbonate P – F

O C O O

C O

 

511 573 869 1086 1437 1493

0.0 0.5

561 725 780 847 903 1086 1194 1313 1407 1638 1776 1806

0.0 0.5

716 776 892 974 1071 1160 1220 1392 1422 1478 1552 1772 1798 1862 1959

0.0 0.5 1.0 1.5 500 1000 1500 2000

SLIDE 38

XPS spectra of nano-LiNi0.5Mn0.5O2 particles

peak at 686 eV: LiF, MnF2, NiF2 peaks at 855 eV and at 861.3 eV : formation of surface species containing Ni of higher oxidation state than 2+. peak at 529.7 eV: nickel (III) oxide and manganese oxides. a satellite peak at 531.7 eV: organic species with carbonyl groups

Ageing in solution Changes in surface chemistry and passivation

Ni Ni Oxygen F F Oxygen Pristine Aged at 600C

Surface chemistry

SLIDE 39

1. Both LiNi0.5Mn1.5O4 and LiNi0.5Mn0.5O2 nano-materials can be

apparently chemically stable in standard electrolyte solutions,

2. These materials develop unique surface chemistry in standard

solutions.

3. Clear advantages to the use core-shell carbon coated nano V2O5
4. LiFePO4 is a promising cathode material, provided that the

solutions do not contain acidic contaminants.

5. Ionic liquids can replace standard solutions and may provide

much better safety features for Li ion batteries. We Already demonstrated the possibility to use very high capacity Si electrodes and high voltage Li[Mn,Ni]O2 cathodes. Much more work is needed.

6. We demonstrated the clear advantages of the new electrolyte: Li