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|Title:||Synthesis and Characterization Studies of Li-Fe-In-(PO4) Phases: Chemical Relatives of Battery Cathode Material Lithium Iron Phosphate|
|Authors:||Khalifah, Peter G|
Saccomanno, Michael Richard
Department of Chemistry.
|Publisher:||The Graduate School, Stony Brook University: Stony Brook, NY.|
|Abstract:||Lithium iron(II) phosphate, also known as lithium ferrophosphate (LiFePO<sub>4</sub>, LFP), has been the subject of many recent energy storage studies. As a battery cathode material, LFP has many advantages for commercial applications. Compared to its competitors like LiMn<sub>2</sub>O<sub>4</sub> and the ubiquitous but carcinogenic LiCoO<sub>2</sub>, LFP (specific energy = 600 Wh/kg) exhibits low toxicity, low cost, good thermal stability, and excellent electrochemical performance at high charge/discharge rates. As part of the efforts to understand and improve LFP, a great amount of research has been committed towards developing, characterizing, and electrochemically testing chemical relatives of this phase. In this work, chemical relatives of LFP belonging to the Li<sub>3</sub>PO<sub>4</sub>-Fe<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub>-InPO<sub>4</sub> phase system were investigated. This has lead to the discovery of lithium iron(II) indium phosphate [LiFeIn(PO<sub>4</sub>)<sub>2</sub>, LFIP]. Structural studies on LFIP using laboratory and synchrotron X-ray, neutron, and electron diffraction techniques have demonstrated this phase to crystallize in the orthorhombic space group <italic>Pbca</italic> with lattice parameters <italic>a</italic> = 9.276(1) Ã…, <italic>b</italic> = 13.757(2) Ã…, and <italic>c</italic> = 9.476(1) Ã…. Unlike LFP, this new material does not perform well as a battery cathode as found by chemical delithiation tests, electrochemical cycling, and bond-valence sum difference maps of Li<super>+</super> diffusion pathways. LFIP has also been characterized by magnetic and optical measurements. The material does not order magnetically above 2 K, is paramagnetic with weak antiferromagnetic interactions, and has an effective magnetic moment of 5.39 <italic>Âµ</italic><sub>B</sub>/Fe. LFIP has a band-gap energy of 2.94 eV and d orbital ligand field splitting energies of 0.75 eV and 0.99 eV. Based on our synthesis results, a preliminary assessment of the Li<sub>3</sub>PO<sub>4</sub>-Fe<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub>-InPO<sub>4</sub> phase system is presented.|
|Appears in Collections:||Stony Brook Theses and Dissertations Collection|
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