Lithium iron phosphate (LiFePO4) for lithium-ion batteries is considered as perfect cathode material for various military applications, especially underwater combat vehicles. For deployment at high rate applications, the low conductivity of LiFePO4 needs to be improved. Cationic substitution of niobium in the native carbon coated LiFePO4 is one of the methods to enhance the conductivity. In the present work, how the niobium doped solid solution could be formed is studied. Nanopowders of LiFePO4/C and Li1−xNbxFePO4/C (x = 0.05, 0.1, 0.15, 0.16) are synthesized from precursors using microwave synthesis. The solid solution formation up to (x = 0.15) Li1−xNbxFePO4/C without impurity phases is confirmed by X-ray diffraction (XRD) pattern and Fourier transform infrared spectroscopic (FTIR) results. Particle distribution is obtained by scanning electron microscope from the synthesized powders. Energy dispersive X-ray spectrometer (EDS) results qualitatively confirmed the presence of niobium. Also, direct current (dc) conductivities are measured using sintered pellets and activation energies are calculated using Arrhenius equation. The dependence of conductivity and activation energy of LiFePO4/C on variation of niobium doping is investigated in this study. CR2032 type coin cells are fabricated with the synthesized materials and subjected to cyclic voltammetry studies, rate capability and cycle life studies. Diffusion coefficients are obtained from electrochemical impedance spectroscopy studies. It is observed that room temperature dc conductivity improved by niobium doping when compared to LiFePO4/C (0.379 × 10−2 S/cm) and is maximum for Li0.9Nb0.1FePO4/C (40.58 × 10−2 S/cm). It is also observed that diffusion coefficient of Li+ in Li0.9Nb0.1FePO4/C (13.306 × 10−9 cm2 s−1) improved by two orders of magnitude in comparison with the pure LiFePO4 (10 − 12 cm2 s−1) and carbon-coated nano LiFePO4/C (0.632 × 10−11 cm2 s−1). Cells with Li0.9Nb0.1FePO4/C are able to deliver useful capacity of around 104 mAh/g at 10 C rate. More than 500 cycles are achieved with Li0.9Nb0.1FePO4/C at 20 C rate.

References

References
1.
Padhi
,
A. K.
,
Nanjundaswamy
,
K. S.
, and
Goodenough
,
J. B.
,
1997
, “
Phospho-Olivines as Positive Electrode Materials for Rechargeable Lithium Batteries
,”
J. Electrochem. Soc.
,
144
(
4
), pp.
1188
1194
.
2.
Tang
,
K.
,
Sun
,
J.
,
Yu
,
X.
,
Li
,
H.
, and
Huang
,
X.
,
2009
, “
Electrochemical Performance of LiFePO4 Thin Films With Different Morphology and Crystallinity
,”
Electrochim. Acta
,
54
(
26
), pp.
6565
6569
.
3.
Jiang
,
J.
, and
Dahn
,
J. R.
,
2004
, “
ARC Studies of the Thermal Stability of Three Different Cathode Materials: LiCoO2; Li [Ni0.1Co0.8Mn0.1]O2; and LiFePO4, in LiPF6 and LiBoB EC/DEC Electrolytes
,”
Electrochem. Commun
,
6
(
1
), pp.
39
43
.
4.
Yamada
,
A.
,
Koizumi
,
H.
,
Nishimura
,
S.-I.
,
Sonoyama
,
N.
,
Kanno
,
R.
,
Yonemura
,
M.
,
Nakamura
,
T.
, and
Kobayashi
,
Y.
,
2006
, “
Room-Temperature Miscibility Gap in LixFePo4
,”
Nat. Mater.
,
5
(
5
), pp.
357
360
.
5.
Morgan
,
D.
,
Van der Ven
,
A.
, and
Ceder
,
G.
,
2004
, “
Li Conductivity in LixMPO4 (M = Mn, Fe, Co, Ni) Olivine Materials
,”
Electrochem. Solid State Lett.
,
7
(
2
), pp.
A30
A32
.
6.
Islam
,
M. S.
,
Driscoll
,
D. J.
,
Fisher
,
C. A. J.
, and
Slater
,
P. R.
,
2005
, “
Atomic Scale Investigation of Defects, Dopants, and Lithium Transport in a LiFePO4 Olivine-Type Battery Material
,”
Chem Mater.
,
17
(
20
), pp.
5085
5092
.
7.
Nishimura
,
S.
,
Kobayashi
,
G.
,
Ohoyama
,
K.
,
Kanno
,
R.
,
Yashima
,
M.
, and
Yamada
,
A.
,
2008
, “
Experimental Visualization of Lithium Diffusion of LixFePO4
,”
Nat. Mater.
,
7
(
9
), pp.
707
711
.
8.
Malik
,
R.
,
Burch
,
D.
,
Bazant
,
M.
, and
Ceder
,
G.
,
2010
, “
Particle Size Dependence of the Ionic Diffusivity
,”
Nano Lett.
,
10
(
10
), pp.
4123
4127
.
9.
Chang
,
Z. R.
,
Lv
,
H. J.
,
Tang
,
H. W.
,
Li
,
H. J.
,
Yuan
,
X. Z.
, and
Wang
,
H.
,
2009
, “
Synthesis and Characterization of High Density LiFePO4/C Composites as Cathode Materials for Lithium Ion Batteries
,”
Electrochim. Acta
,
54
(
20
), pp.
4595
4599
.
10.
Sun
,
C. S.
,
Zhou
,
Z.
,
Xu
,
Z. G.
,
Wang
,
D. G.
,
Wei
,
J. P.
, and
Bian
,
X. K.
,
2009
, “
Improved High-Rate Charge/Discharge Performances of LiFePO4 Via V-Doping
,”
J. Power Sources
,
193
(
2
), pp.
841
845
.
11.
Konarova
,
M.
, and
Taniguchi
,
I.
,
2009
, “
Physical and Electrochemical Properties of LiFePO4 Nanoparticles Synthesized by a Combination of Spray Pyrolysis With Wet Ball Milling
,”
J. Power Sources
,
194
(
2
), pp.
1029
1035
.
12.
Zhao
,
B.
,
Jiang
,
Y.
,
Zhang
,
H.
,
Tao
,
H.
,
Zhong
,
M.
, and
Jiao
,
Z.
,
2009
, “
Morphology and Electrical Properties of Carbon Coated LiFePO4 Cathode Materials
,”
J. Power Sources
,
189
(
1
), pp.
462
466
.
13.
Wu
,
S.-h.
,
Chen
,
M.-S.
,
Chien
,
C.-J.
, and
Fu
,
Y.-P.
,
2009
, “
Preparation and Characterization of TI4+—Doped LiFePO4 Cathode Materials for Lithium-Ion Batteries
,”
J. Power Sources
,
189
(
1
), pp.
440
444
.
14.
Zhang
,
Y.
,
Huo
,
Q.-y.
,
Du
,
P.-P.
,
Wang
,
L.-Z.
,
Zhang
,
A.-Q.
,
Song
,
Y.-h.
,
Lv
,
Y.
, and
Li
,
G.-y.
,
2012
, “
Advances in New Cathode Material LiFePO4 for Lithium-Ion Batteries
,”
Synth. Met.
,
162
(
13–14
), pp.
1315
1326
.
15.
Chen
,
X.-J.
,
Zhao
,
X.-B.
,
Cao
,
G.-S.
,
Ma
,
S.-L.
,
Xie
,
J.
, and
Zhu
,
T.-J.
,
2006
, “
Electrochemical Properties of Nb Doped LiFePO4/C Prepared by One-Step Solid-State Synthesis
,”
Chin. J. Nonferrous Met.
,
16
(
10
), pp.
1665
1671
.http://en.cnki.com.cn/Article_en/CJFDTOTAL-ZYXZ200610002.htm
16.
Park
,
C. K.
,
Park
,
S. B.
,
Oh
,
S. H.
,
Jang
,
H.
, and
Cho
,
W. I.
,
2011
, “
Bull. Lorean, Li Ion Diffusivity and Improved Electrochemical Performances of the Carbon Coated LiFePO4
,”
Chem. Soc.
,
32
(
3
), pp.
836
840
.
17.
Shin
,
H. C.
,
Cho
,
W. I.
, and
Jang
,
H.
,
2006
, “
Electrochemical Properties of the Carbon Coated LiFePO4 as a Cathode Material for Lithium-Ion Secondary Batteries
,”
J. Power Sources
,
159
(
2
), pp.
1383
1388
.
18.
Wurm
,
C.
,
Morcrette
,
M.
,
Gwizdala
,
S.
, and
Masquelier
,
C.
,
2002
, “
Lithium Transition-Metal Phosphate Powder for Rechargeable Batteries
,” Patent No. CNRS-UMICORE, #WO 02/099913 A1.
19.
Higuchi
,
M.
,
Katayama
,
K.
,
Azuma
,
Y.
,
Yukawa
,
M.
, and
Suhara
,
M.
,
2003
, “
Synthesis of LiFePO4 Cathode Material by Microwave Processing
,”
J. Power Sources
,
119–121
, pp.
258
261
.
20.
Park
,
K. S.
,
Son
,
J. T.
,
Chung
,
H. T.
,
Kim
,
S. J.
,
Kim
,
C. H.
,
Lee
,
C. H.
, and
Kim
,
H. G.
,
2003
, “
Synthesis of LiFePO4 by Co-Precipitation and Microwave Heating
,”
Electrochem. Commun.
,
5
(
10
), pp.
839
842
.
21.
Wang
,
L.
,
Huang
,
Y.
,
Jiang
,
R.
, and
Jia
,
D.
,
2007
, “
Preparation and Characterization of Nanosized LiFePO4 by Low Heating Solidstate Coordination Method and Microwave Heating
,”
Electrochim. Acta
,
52
(
24
), pp.
6778
6783
.
22.
Beninati
,
S.
,
Damen
,
L.
, and
Mastragostino
,
M.
,
2008
, “
MW Assisted Synthesis of LiFePO4 for High Power Applications
,”
J. Power Sources
,
180
(
2
), pp.
875
879
.
23.
Murugan
,
A. V.
,
Muraliganth
,
T.
, and
Manthiram
,
A.
,
2008
, “
Rapid Microwave Solvothermal Synthesis of Phosphor Olivine Nanorods and Their Coating With a Mixed Conducting Polymer for Lithium Ion Batteries
,”
Electrochem. Commun.
,
10
(
6
), pp.
903
906
.
24.
Bykov
,
Y. V.
,
Rybakov
,
K. I.
, and
Semenov
,
V. E.
,
2001
, “
High Temperature Microwave Processing of Materials
,”
J. Phys. D: Appl. Phys.
,
34
(
13
), pp.
R55
R75
.
25.
Li
,
W.
,
Ying
,
J.
,
Wan
,
C.
,
Jiang
,
C.
,
Gao
,
J.
, and
Tang
,
C.
,
2007
, “
Preparation and Characterization of LiFePO4 From NH4FePO4 H2O Under Different Microwave Heating Conditions
,”
J. Solid State Electrochem.
,
11
(
6
), pp.
799
803
.
26.
Zhang
,
Y.
,
Feng
,
H.
,
Wu
,
X.
,
Wang
,
L.
,
Zhang
,
A.
,
Xia
,
T.
,
Dong
,
H.
, and
Liu
,
M.
,
2009
, “
Onestep Microwave Synthesis and Characterization of Carbon Modified Nanocrystalline LiFePO4
,”
Electrochim. Acta
,
54
(
11
), pp.
3206
3210
.
27.
Ong
,
S. P.
,
Chevrier
,
V. L.
, and
Ceder
,
G.
,
2011
, “
Comparison of Small Polaron Migration and Phase Separation in Olivine LiMnPO4 and LiFePO4 Using Hybrid Density Functional Theory
,”
Phys. Rev. B
,
83
(
7
), p.
075112
.
28.
Shahid
,
R.
, and
Murugavel
,
S.
,
2013
, “
Particle Size Dependent Confinement and Lattice Strain Effects in LiFePO4
,”
Phys. Chem. Chem. Phys
,
15
(
43
), pp.
18809
18814
.
29.
Molenda
,
J.
,
Kulka
,
A.
,
Milewska
,
A.
,
Zając
,
W.
, and
Swierczek
,
K.
,
2013
, “
Structural, Transport and Electrochemical Properties of LiFePO4 Substituted in Lithium and Iron Sublattices (Al, Zr, W, Mn, Co and Ni)
,”
Mater.
,
6
(
5
), pp.
1656
1687
.
30.
Yabuuchi
,
N.
,
Kubota
,
K.
,
Aoki
,
Y.
, and
Komaba
,
S.
,
2016
, “
Understanding Particle-Size-Dependent Electrochemical Properties of Li2MnO3-Based Positive Electrode Materials for Rechargeable Lithium Batteries
,”
J. Phys. Chem. C
,
120
(2), pp. 875–885.
31.
Chung
,
S.-Y.
,
Bloking
,
J.
, and
Chiang
,
Y.-M.
,
2002
, “
Electronically Conductive Phosphor-Olivines as Lithium Storage Electrodes
,”
Nat. Mater.
,
1
(
2
), pp.
123
128
.
32.
Chung
,
S.-Y.
, and
Chiang
,
Y.-M.
,
2003
, “
Microscale Measurements of the Electrical Conductivity of Doped LiFePO4
,”
Electrochem. Solid State Lett.
,
6
(
12
), pp.
A278
A281
.
33.
Nakamura
,
T.
,
Miwa
,
Y.
,
Tabuchi
,
M.
, and
Yamada
,
Y.
,
2006
, “
Structural and Surface Modifications of LiFePO4 Olivine Particles and Their Electrochemical Properties
,”
J. Electrochem. Soc.
,
153
(
6
), pp.
A1108
A1114
.
34.
Zhang
,
D. Y.
,
Zhang
,
L.
,
Zhang
,
P. X.
,
Lin
,
M. C.
,
Huang
,
X. Q.
,
Ren
,
X. Z.
, and
Xu
,
Q. M.
,
2010
, “
Modification of LiFePO4 by Citric Acid Coating and Nb5+ Doping
,”
J. Adv. Mater. Res.
,
158
, pp.
167
173
.
35.
Satyavani
,
T. V. S. L.
,
Srinivas Kumar
,
A.
, and
Subbarao
,
P. S. V.
,
2014
,
Physics of Semiconductor Devices, Environmental Science and Engineering
,
Springer International Publishing
, Cham,
Switzerland
, pp.
721
723
.
36.
Julian
,
C.
,
Rougier
,
C. J.
, and
Nazri
,
G. A.
,
1997
, “
Synthesis, Structure, Lattice Dynamics and Electrochemistry of Lithiated Manganese Spinel (LiMn2O4)
,”
Mater. Res. Soc. Proc.
,
453
, pp.
647
653
.
37.
Rouier
,
A.
,
Nazri
,
G. A.
, and
Julien
,
C.
,
1997
, “
Vibrational Spectroscopy and Electrochemical Properties of LiNi0.7Co0.3O2 Cathode Materials for Rechargeable Lithium Batteries
,”
Ionics
,
3
(
3–4
), pp.
170
176
.
38.
Julien
,
C. M.
,
Jozwiak
,
P.
, and
Garbarczyk
,
J.
, 2004, “
Advanced Techniques for Energy Sources Investigating and Testing
,”
International Workshop
, Sofia, Bulgaria, L4-1, Sept. 4–9.
39.
Takahashi
,
M.
,
Tobishima
,
S.-I.
,
Takei
,
K.
, and
Sakurai
,
Y.
,
2002
, “
Reaction Behaviour of LiFePO4 as a Cathode Material for Rechargeable Lithium Batteries
,”
Solid State Ionics
,
148
(
3–4
), pp.
283
289
.
40.
Novikova
,
A. S.
, and
Yaroslavtsev
,
B. A.
,
2017
Cathode Materials Based on Olivine Lithium Iron Phosphates for Lithium-Ion Batteries
,”
Rev. Adv. Mater. Sci.
,
49
, pp.
129
139
.http://www.ipme.ru/e-journals/RAMS/no_24917/02_24917_novikova.pdf
41.
Kim
,
D. J.
,
Ponraj
,
R.
,
Kannan
,
A. G.
,
Lee
,
H.-W.
,
Fathi
,
R.
,
Ruffo
,
R.
,
Mari
,
C. M.
, and
Kim
,
D. K.
,
2013
, “
Diffusion Behaviour of Sodium Ions in Na0.44MnO2 in Aqueous and Non-Aqueous Electrolytes
,”
J. Power Sources
,
244
, pp.
758
763
.
42.
Kandhasamy
,
S.
,
Nallathamby
,
K.
, and
Minakshi
,
M.
,
2012
, “
Role of Structural Defects in Olivine Cathodes
,”
Prog. Solid State Chem.
,
40
(
1–2
), pp.
1
5
.
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