Neeraj Sharma

Neeraj Sharma

Neeraj Sharma

B.Sc. (Adv.) (Hons) Sydney 2005, Ph.D. Sydney 2010, MRACI

Senior Lecturer & ARC DECRA Fellow

Contact details

Phone: +61 2 9385 4714
Email: neeraj.sharma@unsw.edu.au

Office

Room 216, Dalton Building
UNSW, Kensington, 2052

 

Research Group Website

/research/research-groups/sharma-group

Biographical Details

Bachelor of Advanced Science (Honours Class 1), The University of Sydney, 2002-2005. Ph.D. in Chemistry, The University of Sydney, 2006-2009. Postdoctoral researcher, The Bragg Institute, Australian Nuclear Science and Technology Organisation 2009-2012. Australian Institute of Nuclear Science and Engineering (AINSE) Research Fellowship and appointed Lecturer in Chemistry, UNSW, 2012.

Research Interests

Solid state and Materials Chemistry

Energy-related devices such as batteries and fuel cells are essential in our lives. In order to develop the next generation of technologies we need more power, or better performance, at a lower environmental cost. Research into understanding the interplay between the crystal structure of new materials and their physical properties will allow us to revolutionise how we obtain and store energy.

My research approach encompasses exploratory synthesis, structural determination, physical property measurements and in situ structure and property characterisation of batteries and other devices.

Towards the next generation of batteries: Sodium-ion batteries

Lithium-ion batteries are ubiquitous in our daily lives, e.g. mobile phones and laptop computers, but their limitations have restricted wide-scale use in applications requiring higher power, e.g. electric vehicles and energy storage of renewable energy. This project will target new battery chemistries, in particular sodium-ion batteries, by developing and characterizing new electrode and electrolyte materials. We will work to develop a reliable and affordable room-temperature sodium-ion battery to provide sufficient power for large-scale energy storage from intermittent renewable power sources. Students will work on one of the following parts of a battery and test their component in idealized batteries.

  • Positive electrode materials

These electrodes provide the source of the sodium-ions and represent the largest cost and energy limitations for lithium-ion batteries. Here, new sodium-containing transition metal oxides, phosphates or sulfates are be synthesized and characterized to determine the relationship between crystal structure and battery performance.

  • Electrolytes

Sodium-ion conducting ceramics or glassy-ceramics are known to be excellent electrolytes at high temperatures (>300°C). We work towards making materials with sufficient sodium-ion conduction at room temperature.

  • Negative electrode materials

Negative electrodes are the least investigated component in a sodium-ion battery and the compounds used for lithium-ion batteries show poor performance in sodium-ion batteries. By developing new negative electrodes and understanding their limitations towards reversible sodium insertion/extraction we will be enable the next generation of devices. The focus of these projects are carbon based materials and the use of solid state 23Na NMR to characterise the insertion/extraction processes.

New: Tuning negative thermal expansion to produce zero thermal expansion materials

The majority of materials expand during heating via thermal expansion and this process is responsible for billions of dollars per year in maintenance, re-manufacture and replacement costs due to wear and tear on both moving parts (e.g. in aircraft gas turbines), and components that are designed to be static (e.g. in optics, coatings, electronics). If a zero thermal expansion (ZTE) material can be made, a material that neither expands nor contracts upon heating, this could dramatically reduce industrial costs. In order to achieve this, the opposite extreme of materials are considered in this project - negative thermal expansion (NTE) is a property exhibited by a small group of materials predominantly due to transverse vibrations of atom groups or cooperative rotations of units (e.g. –CN- or WO4). These materials typically feature large crystallographic voids and cations with variable oxidation states. So why not use a battery as a synthesis tool? In this project we will controllably insert Li and Na into the voids of the NTE materials, via a battery, in order to tune the cooperative rotations to produce ZTE materials.

In situ studies of materials

Investigating materials functioning in actual devices, i.e. in situ, allows the direct comparison of device performance to the atomic-level changes in the material. By manipulating the atomic-scale crystal structure of components, using a variety of synthetic techniques, improvements in device performance can be achieved, e.g. better lithium-ion batteries can be made.

In a lithium-ion battery, the charge process is characterised by the removal of lithium from the cathode, while on discharge lithium is inserted into the cathode. The cathode above features relatively small crystal-structure changes with the lithium insertion/extraction (top) making it an attractive material for commercial applications. The information on crystal-structure evolution is derived from in situ neutron powder diffraction data (bottom left) during charge/discharge cycling of the battery. The battery (bottom right) was fabricated by collaborators in Fudan University, China.

Development of new ionic conductors

Full solid-state devices are more advantageous than liquid-containing devices as they are generally safer and more robust under harsh conditions however limitations arise particularly due to the lower ionic conductivity in solids. Exploring the mechanism of ionic conduction in solids, and its relationship to factors such as temperature and dopant concentration is a method to significantly improve solid-state devices.

An example of ‘watching’ a synthesis reaction using neutron powder diffraction. Starting materials are placed on the diffractometer and the synthesis procedures are initiated while neutron powder diffraction patterns are continuously collected. For Li6PS5Cl the synthesis temperature is found to have a significant influence on the ionic conduction properties.

Structural investigations using neutron and X-ray scattering

Single crystal, solid-state and electrochemical synthetic techniques can be used to tailor-make new materials for specific applications, but critical to this process is the characterisation tools employed to elucidate the arrangement of atoms. Our use of the Australian Synchrotron and the neutron scattering facilities at ANSTO provide unparalleled insight into these materials.

 

Selected Publications

Towards the next generation of batteries: Sodium-ion batteries

  • N. Sharma, N. Tapia-Ruiz, G. Singh, A. R. Armstrong, J. C. Pramudita, H. E. A. Brand, J. Billaud, P. G. Bruce, T. Rojo, Rate dependent performance related to crystal structure evolution of Na0.67Mn0.8Mg0.2O2 in a sodium-ion battery, Chemistry of Materials, 27, 6976−6986 (2015)
  • V. Palomares, P. Serras, H.E.A. Brand, T. Rojo, N. Sharma, Structural evolution of mixed valent (V3+/V4+) and V4+ sodium vanadium fluorophosphates as cathodes in sodium-ion batteries: Comparisons, overcharging and mid-term cycling, Journal of Materials Chemistry A, 3, 23017-23027 (2015)
  • N. Sharma, M. H. Han, J. C. Pramudita, E. Gonzalo, H. E. A. Brand, T. Rojo, A comprehensive picture of the current rate dependence on the structural evolution of P2-Na2/3Fe2/3Mn1/3O2, Journal of Materials Chemistry A, 3, 21023–21038 (2015)
  • N. Sharma, E. Gonzalo, J. C. Pramudita, M. H. Han, H. E. A. Brand, J. N. Hart, W. K. Pang, Z. Guo, T. Rojo, The unique structural evolution of the O3-phase Na2/3Fe2/3Mn1/3O2 during high rate charge/discharge: A sodium-centred perspective, Advanced Functional Materials, 25, 4994-5005 (2015)
  • J. C. Pramudita, S. Schmid, T. Godfrey, T. Whittle, M. Alam, T. Hanley, H. E. A. Brand, N. SharmaSodium uptake in cell construction and subsequent in operando electrode behaviour of Prussian Blue Analogues, Fe[Fe(CN)6]1-x×yH2O and FeCo(CN)6, Physical Chemistry Chemical Physics, 16, 24178-24187 (2014)

In situ studies on materials

Reviews & books

  • N. Sharma, M. Wagemaker, “Lithium-Ion Batteries” in Neutron Applications in Materials for Energy, GJ Kearley, VK Peterson (Ed), Springer, p139-203, http://link.springer.com/chapter/10.1007/978-3-319-06656-1_7
  • N. Sharma, W. K. Pang, Z. Guo, V. K. Peterson, In situ powder diffraction studies of electrode materials in rechargeable batteries, ChemSusChem, 8, 2826 – 2853 (2015)

Journal articles

  • J. Li, R. Petibon, S. Glazier, N. Sharma, W. K. Pang, V. K. Peterson, J. R. Dahn, In-situ Neutron Diffraction Study of a High Voltage Li(Ni0.42Mn0.42Co0.16)O2/Graphite Pouch Cell, Electrochimica Acta, 180, 234–240 (2015)
  • N. Sharma, G. Du, Z. Guo, J. Wang, Z. Wang, V. K. Peterson, Direct evidence of concurrent solid-solution and two-phase reactions and the non-equilibrium structural evolution of LiFePO4, Journal of the American Chemical Society, 134, 7867-7873 (2012)
  • N. Sharma, V. K. Peterson, In situ neutron diffraction experiments on lithium-ion batteries, Journal of Solid State Electrochemistry, 16, 1849-1856, (2012)
  • G. Du, N. Sharma, V. K. Peterson, J. Kimpton, Z. Guo, Br-doped Li5Ti4O12 and composite TiO2 anodes for Li-ion batteries: Synchrotron X-ray and in-situ neutron diffraction studies, Advanced Functional Materials, 21, 3990-3997, (2011)
  • N. Sharma, M. V. Reddy, G. Du, S. Adams, G. V. Subba Rao, B. V. R. Chowdari, Z. Guo, V. K. Peterson, Time-dependent in-situ neutron diffraction investigation of Li(Co0.16Mn1.84)O4 cathode, Journal of Physical Chemistry C, 115, 21473-21480, (2011)
  • N. Sharma, G. Du, A. J. Studer, Z. Guo, V. K. Peterson, Structure of the MoS2 anode within a Li-ion battery during discharge: in-situ neutron diffraction studies using an optimised cell design, Solid State Ionics, 199-200, 37-43, (2011)
  • N. Sharma, V. K. Peterson, M. M. Elcombe, M. Avdeev, A. J. Studer, N. Blagojevic, R. Yusoff, N. Kamarulzaman, Structural changes in a commercial lithium ion battery during electrochemical cycling: An in-situ neutron diffraction study, Journal of Power Sources, 195, 8258-8266 (2010)

Development of new ionic conductors

  • D. Safanama, N. Sharma, R. Prasada Rao, H. E. A. Brand and S. Adams, Structural evolution of NASICON-type Li1+xAlxGe2-x(PO4)3 using in situ synchrotron X-ray powder diffraction, Journal of Materials Chemistry A, 2016, DOI:10.1039/C6TA00402D, Accepted April 2016
  • R.P. Rao, W. Gu, N. Sharma, V.K. Peterson, M. Avdeev, S. Adams, In situ Neutron Diffraction Monitoring of Li7La3Zr2O12 formation: Towards a Rational Synthesis of Garnet Solid Electrolytes, Chemistry of Materials, 27, 2903–2910 (2015)

Structural investigations using neutron and X-ray scattering

  • R.J. Gummow, N. Sharma, V.K. Peterson and Y. He, Crystal chemistry of the Pmnb polymorph of Li2MnSiO4, Journal of Solid State Chemistry 188, 32-37, (2012) - Journal cover
  • W. Miiller, Q. Zhou, N. Sharma, M. Avdeev, R. Kutteh, G. J. Kearley, B. J. Kennedy, S. A. Schmid and C. D. Ling, An extraordinary magnetoelastic effect in Ba3BiIr2O9 due to coincident magnetic dimerisation and structural antidimerisation, Journal of the American Chemical Society, 134, 3265-3270 (2012)
  • N. Sharma, R. B. Macquart, M. Avdeev, M. Christensen, G. J. McIntyre, Y. Chen, C. D. Ling, Re-investigation of the Structure and Crystal Chemistry of the Bi2O3-W2O6 'Type Ib' Solid Solution Using Single Crystal Neutron and Synchrotron X-ray Diffraction, Acta Crystallographica Section, B66, p165-172 (2010)
  • N. Sharma, G. E. Wrighter, P. Y. Chen, B. J. Kennedy, P. L. Lee, C. D. Ling, Three-layer Aurivillius phases containing magnetic transition metal cations: Bi(2-x)Sr(2+x)(Nb,Ta)(2+x)M(1-x)O12, M=Ru4+, Ir4+, Mn4+, x≈0.5, Journal of Solid State Chemistry, 180, p370-376 (2007)