nanoparticles; lithium metal phosphates; microwave chemistry; battery applications; electrochemistry; Lithium iron phosphate
Carriazo D, Rossell MD, Zeng GB, Bilecka I, Erni R, Niederberger M (2012), Formation Mechanism of LiFePO4 Sticks Grown by a Microwave-Assisted Liquid-Phase Process, in SMALL
, 8(14), 2231-2238.
Bilecka I, Luo L, Djerdj I, Rossell MD, Jagodic M, Jaglicic Z, Masubuchi Y, Kikkawa S, Niederberger M (2011), Microwave-Assisted Nonaqueous Sol-Gel Chemistry for Highly Concentrated ZnO-Based Magnetic Semiconductor Nanocrystals, in JOURNAL OF PHYSICAL CHEMISTRY C
, 115(5), 1484-1495.
Bilecka I, Hintennach A, Rossell MD, Xie D, Novak P, Niederberger M (2011), Microwave-assisted solution synthesis of doped LiFePO4 with high specific charge and outstanding cycling performance, in JOURNAL OF MATERIALS CHEMISTRY
, 21(16), 5881-5890.
Bilecka I, Kubli M, Amstad E, Niederberger M (2011), Simultaneous formation of ferrite nanocrystals and deposition of thin films via a microwave-assisted nonaqueous sol-gel process, in JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY
, 57(3), 313-322.
Bilecka I, Niederberger M (2010), Microwave chemistry for inorganic nanomaterials synthesis, in NANOSCALE
, 2(8), 1358-1374.
Kubli M, Luo L, Bilecka I, Niederberger M (2010), Microwave-Assisted Nonaqueous Sol-Gel Deposition of Different Spinel Ferrites and Barium Titanate Perovskite Thin Films, in CHIMIA
, 64(3), 170-172.
Bilecka I, Niederberger M (2010), New developments in the nonaqueous and/or non-hydrolytic sol-gel synthesis of inorganic nanoparticles, in ELECTROCHIMICA ACTA
, 55(26), 7717-7725.
Bilecka I, Hintennach A, Djerdj I, Novak P, Niederberger M (2009), Efficient microwave-assisted synthesis of LiFePO4 mesocrystals with high cycling stability, in JOURNAL OF MATERIALS CHEMISTRY
, 19(29), 5125-5128.
Bilecka I, Elser P, Niederberger M (2009), Kinetic and Thermodynamic Aspects in the Microwave-Assisted Synthesis of ZnO Nanoparticles in Benzyl Alcohol, in ACS NANO
, 3(2), 467-477.
The objective of the proposed research is directed towards the development of nonaqueous liquid-phase synthesis routes to lithium transition metal phosphates LiMPO4 (M=Mn, Fe, Co, Ni) using microwave irradiation as heating tool, and study of the electrochemical properties with respect to their application as cathode material in lithium ion batteries.Lithium transition metal phosphates are one of the most promising candidates to replace the expensive and oxidatively unstable LiCoO2 in cathodes of secondary lithium batteries. LiFePO4 for example has a discharge voltage of about 3.4 V vs. lithium, shows no obvious fading even after several hundred cycles, exhibits high power capabilities, and its theoretical energy density is 550 W h/kg, which is higher than obtained in commercial LiCoO2 cells. Moreover, it is very stable during discharge/recharge, can be produced from low-price components and is non-toxic. Remaining challenges are how to make these materials by a low-cost process, ideally involving no energy intensive high temperature firing, and how to increase its electronic conductivity.The first part of the research project deals with the elaboration of synthesis routes to phospho-olivine nanoparticles involving the microwave-mediated reaction of various molecular precursors in organic solvents at temperatures less than 200 °C. Preliminary results (see Section 2.3) have already proven that it is possible to directly produce nanocrystalline LiFePO4 in benzyl alcohol at 200 °C after just a few minutes of microwave irradiation. However, these synthesis protocols have to be reproduced, optimized and extended to other phospho-olivines such as LiMnPO4, LiCoPO4, and LiNiPO4. Systematic variation of precursor-solvent combinations will make it possible to prepare lithium transition metal phosphates with different particle sizes and shapes.In a next step the electrochemical properties of these nanopowders have to be studied. These investigations will be performed at the Electrochemistry Laboratory of the Paul Scherrer Institute in Villigen in close collaboration with the group of Dr. Petr Novak. If the electrochemical properties exhibit size- and shape-dependent behaviour, the morphology of the nanoparticles will be optimized with respect to their performance as cathode material.Another integral part of the project is the chemical modification of the lithium transition metal phosphate nanoparticles to increase the electronic conductivity. We foresee two possibilities, namely doping with supervalent ions or including a conductive phase. Although these ideas are not new, we know from our experience with metal oxides that microwave irradiation is particularly suitable for the preparation of doped materials, as well as for the synthesis of core-shell-like structures.In summary, the proposed research will target the following goals:i)Development of synthesis routes to nanocrystalline lithium transition metal phosphates with high crystallinity using microwave irradiation as heating toolii)Systematic variation of precursor-solvent combination to achieve different particle sizes and shapesiii)Fabrication of electrodes and study of the electrochemical propertiesiv)Modification of the electrical conductivity of the lithium metal phosphate nanoparticles, either by doping with supervalent ions or by coating with a conducting layer (e.g. metal or metal oxides)