ES_O16
New approaches towards lithium nitride anode materials in secondary batteries
1
3
3
2
3
1
Nuria Tapia Ruiz , S Gopukumar , C Nithya , Ronald Smith , J Sobha , Duncan Gregory
1
2
University of Glasgow, Chemistry Department, Joseph Black Building, Glasgow, UK, ISIS Pulsed
Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory,
3
Didcot, UK, Central Electrochemical Research Institute, Karaikudi, India
1
Microwave (MW) reactions offer several advantages over traditional solid state preparation methods .
-1
High temperatures are achievable at extremely rapid heating rates (100 Ks has been reported) plus a
rapid cooling post reaction is achieved. The result is that reaction times are reduced from days to hours
or minutes leading to huge energy savings that are potentially exploitable by industry.
Lithium nitridometallates, Li3-x-yMxN materials (with the Li3N structure, Fig. 1) have been reported
previously as promising anodes in lithium ion batteries, with Li2.6Co0.4N exhibiting the highest reversible
-1 -1 2
capacity (760 mAh g ) . So far, the application of MW methods to the synthesis of ternary and higher
3
nitrides has been limited to the anti-fluorite type nitrides Li3FeN2, Li5TiN3 and Li3AlN2 . We report here
some of our first results of the MW synthesis of a range of Li3-x-yMxN ternary nitrides, where M = Cu, Co
and Ni and x = 0.1 - 0.4. Reaction times for these nitridometallates range from 1 - 15 minutes in contrast
to the 5 -7 days reported in the literature when using conventional high temperature synthesis methods;
a decrease in reation time of up to 4 orders of magnitude. Powder X-ray diffraction (PXD) data for the
MW-synthesized lithium ternary nitrides reveal a decrease of the c parameter and an increase in a as x
increases. Powder neutron diffraction (PND; Fig. 2) has allowed us to locate both the transition metals
+
and Li vacancies in the nitride structures. We can correlate x and y to the reaction parameters and
4,5
compare MW-produced materials to nitiridometallates prepared by conventional means .
Electrochemically testing provides evidence that MW-synthesised materials compare well with those
synthesized by conventional methods.
Fig 2. PND data of
MW-synthesised
Li2.7704Co0.1072N
Fig 1. Lithium nitride-type structure
An alternative strategy to develop high capacity anodes has been to exploit silicon, tin and other
materials that can alloy lithium at high molar ratios. Amorphous silicon and tin can exhibit high capacities
-1
-1
6,7
of up to 1000 mAhg and 993 mAhg respectively . However,
poor cycleability and high irreversible capacity caused by volume
changes during Li insertion and extraction in the first cycle still
need to be overcome. Performance can be improved by the
addition of Li-loaded anode materials to the high capacity anodes
to form composite systems. Lithium transition metal nitrides are
promising candidates for this role. Composites consisting of
Li2.6Co0.4N with either Si, Sn oxides or alloys have been the only
8,9
combinations explored so far . We discuss here some
preliminary studies of new composite electrodes composed of
lithium nitrides with tin to produce materials with reversible
capacity and good cycleability (Fig. 3).
Fig 3. Cycling data for Lithium nitride - tin composite.
1. A.G. Whittaker and D.M.P Mingos, J.Chem.Soc. Dalton Trans.,
1993, 2541
2. M. Nishijima, T. Kagohashi, M. Imanishi, Y. Takeda, O. Yamamoto and S. Kondo, Solid State Ionics,
1996, 83, 107
3. J.D. Houmes and H-C.zur Loye, J.Solid State Chemistry, 1997, 130, 266
4. W. Sachsze and R. Juza, Z. anorg. Chemie, 1949, 259, 278-290
5 A.G. Gordon, R.I Smith, C. Wilson, Z. Stoeva and D.H. Gregory, Chem. Commun. 2004, 2812
6 S. Bourderau, T. Brousse and D.M. Schleich, Journal of Power Sources, 1999, 81-82, 233-236
7. A. .Aboulaich, M. Mouyane, F. Robert, P-E. Lippens, J. Olivier-Fourcade, P. Willmann, J.-C. Jumas,
J. Power Sources., 2007, 174, 1224,
8 J. Yang, Y.Takeda, N. Imanishi and O. Yamamoto, Journal of Electrochemical Society, 2000, 147,
1671-1676
9 J. Yang, Y. Takeda, N. Imanishi and O. Yamamoto, Electrochimica Acta, 2001, 46 (17), 2659-2664